diff --git a/__init__.py b/__init__.py
index 36e44a1..60f7d63 100644
--- a/__init__.py
+++ b/__init__.py
@@ -22,26 +22,27 @@ class Object:
     '''At every place we need an object, but without any requirement on its
        class (methods, attributes,...) we will use this minimalist class.'''
     def __init__(self, **fields):
-        for k, v in fields.iteritems():
+        for k, v in fields.items():
             setattr(self, k, v)
     def __repr__(self):
-        res = u'<Object '
-        for attrName, attrValue in self.__dict__.iteritems():
+        res = '<Object '
+        for attrName, attrValue in self.__dict__.items():
             v = attrValue
             if hasattr(v, '__repr__'):
                 v = v.__repr__()
             try:
-                res += u'%s=%s ' % (attrName, v)
+                res += '%s=%s ' % (attrName, v)
             except UnicodeDecodeError:
-                res += u'%s=<encoding problem> ' % attrName
+                res += '%s=<encoding problem> ' % attrName
         res  = res.strip() + '>'
         return res.encode('utf-8')
-    def __nonzero__(self): return bool(self.__dict__)
+    def __bool__(self):
+        return bool(self.__dict__)
     def get(self, name, default=None): return getattr(self, name, default)
     def __getitem__(self, k): return getattr(self, k)
     def update(self, other):
-        '''Includes information from p_other into p_self'''
-        for k, v in other.__dict__.iteritems():
+        '''Includes information from p_other into p_self.'''
+        for k, v in other.__dict__.items():
             setattr(self, k, v)
     def clone(self):
         res = Object()
@@ -59,11 +60,11 @@ class Hack:
            "_base_<initial_method_name>_". In the patched method, one may use
            Hack.base to call the base method. If p_method is static, you must
            specify its class in p_klass.'''
-        # Get the class on which the surgery will take place
+        # Get the class on which the surgery will take place.
         isStatic = klass
-        klass = klass or method.im_class
-        # On this class, store m_method under its "base" name
-        name = isStatic and method.func_name or method.im_func.__name__
+        klass = klass or method.__self__.__class__
+        # On this class, store m_method under its "base" name.
+        name = isStatic and method.__name__ or method.__func__.__name__
         baseName = '_base_%s_' % name
         if isStatic:
             # If "staticmethod" isn't called hereafter, the static functions
@@ -78,8 +79,8 @@ class Hack:
         '''Allows to call the base (replaced) method. If p_method is static,
            you must specify its p_klass.'''
         isStatic = klass
-        klass = klass or method.im_class
-        name = isStatic and method.func_name or method.im_func.__name__
+        klass = klass or method.__self__.__class__
+        name = isStatic and method.__name__ or method.__func__.__name__
         return getattr(klass, '_base_%s_' % name)
 
     @staticmethod
@@ -87,7 +88,7 @@ class Hack:
         '''Injects any method or attribute from p_patchClass into klass.'''
         patched = []
         added = []
-        for name, attr in patchClass.__dict__.items():
+        for name, attr in patchClass.__dict__.iteritems():
             if name.startswith('__'): continue # Ignore special methods
             # Unwrap functions from static methods
             if attr.__class__.__name__ == 'staticmethod':
diff --git a/bin/asksap.py b/bin/asksap.py
index 3752a5f..193309b 100644
--- a/bin/asksap.py
+++ b/bin/asksap.py
@@ -73,10 +73,10 @@ class AskSap:
                 # Return info about a given function.
                 info = sap.getFunctionInfo(sapElement)
                 prefix = 'Function'
-            print('%s: %s' % (prefix, sapElement))
+            print(('%s: %s' % (prefix, sapElement)))
             print(info)
             sap.disconnect()
-        except SapError, se:
+        except SapError as se:
             sys.stderr.write(str(se))
             sys.stderr.write('\n')
             sys.exit(ERROR_CODE)
diff --git a/bin/backup.py b/bin/backup.py
index 68388a5..33ae555 100644
--- a/bin/backup.py
+++ b/bin/backup.py
@@ -4,7 +4,7 @@ from optparse import OptionParser
 import ZODB.FileStorage
 import ZODB.serialize
 from DateTime import DateTime
-from StringIO import StringIO
+from io import StringIO
 folderName = os.path.dirname(__file__)
 
 # ------------------------------------------------------------------------------
@@ -87,9 +87,9 @@ class ZodbBackuper:
                 w('Try to create backup folder for logs "%s"...' % \
                   self.logsBackupFolder)
                 os.mkdir(self.logsBackupFolder)
-            except IOError, ioe:
+            except IOError as ioe:
                 w(folderCreateError % str(ioe))
-            except OSError, oe:
+            except OSError as oe:
                 w(folderCreateError % str(oe))
         if os.path.exists(self.logsBackupFolder):
             # Ok, we can make the backup of the log files.
@@ -175,7 +175,7 @@ class ZodbBackuper:
         except smtplib.SMTPException, sme:
             w('Error while contacting SMTP server %s (%s).' % \
               (self.options.smtpServer, str(se)))
-        except socket.error, se:
+        except socket.error as se:
             w('Could not connect to SMTP server %s (%s).' % \
               (self.options.smtpServer, str(se)))
 
@@ -191,12 +191,12 @@ class ZodbBackuper:
         for fileName in os.listdir(self.tempFolder):
             ext = os.path.splitext(fileName)[1]
             if ext in self.toRemoveExts:
-                exec '%sCount += 1' % ext[1:]
+                exec('%sCount += 1' % ext[1:])
                 fullFileName = os.path.join(self.tempFolder, fileName)
                 #w('Removing "%s"...' % fullFileName)
                 try:
                     os.remove(fullFileName)
-                except OSError, oe:
+                except OSError as oe:
                     w('Could not remove "%s" (%s).' % (fullFileName, str(oe)))
         w('%d .pdf, %d .doc, %d .rtf and %d .odt file(s) removed.' % \
           (pdfCount, docCount, rtfCount, odtCount))
@@ -268,7 +268,7 @@ class ZodbBackuper:
         if self.emails:
             self.sendEmails()
         self.logFile.close()
-        print(self.logMem.getvalue())
+        print((self.logMem.getvalue()))
         self.logMem.close()
 
 # ------------------------------------------------------------------------------
@@ -302,7 +302,7 @@ class ZodbBackupScript:
             f.write('Hello.')
             f.close()
             os.remove(fileName)
-        except OSError, oe:
+        except OSError as oe:
             raise BackupError('I do not have the right to write in ' \
                               'folder "%s".' % args[1])
         # Check temp folder
@@ -401,7 +401,7 @@ class ZodbBackupScript:
             self.checkArgs(options, args)
             backuper = ZodbBackuper(args[0], args[1], options)
             backuper.run()
-        except BackupError, be:
+        except BackupError as be:
             sys.stderr.write(str(be) + '\nRun the script without any ' \
                                        'argument for getting help.\n')
             sys.exit(ERROR_CODE)
diff --git a/bin/checkldap.py b/bin/checkldap.py
index a517a38..a1c55d3 100644
--- a/bin/checkldap.py
+++ b/bin/checkldap.py
@@ -21,7 +21,7 @@ class LdapTester:
     def __init__(self):
         # Get params from shell args.
         if len(sys.argv) != 8:
-            print(LdapTester.__doc__)
+            print((LdapTester.__doc__))
             sys.exit(0)
         s = self
         s.uri,s.login,s.password,s.base,s.attrs,s.filter,s.scope = sys.argv[1:]
@@ -33,15 +33,15 @@ class LdapTester:
 
     def test(self):
         # Connect the the LDAP
-        print('Connecting to... %s' % self.uri)
+        print(('Connecting to... %s' % self.uri))
         connector = LdapConnector(self.uri)
         success, msg = connector.connect(self.login, self.password)
         if not success: return
         # Perform the query.
-        print ('Querying %s...' % self.base)
+        print(('Querying %s...' % self.base))
         res = connector.search(self.base, self.scope, self.filter,
                                self.attributes)
-        print('Got %d results' % len(res))
+        print(('Got %d results' % len(res)))
 
 # ------------------------------------------------------------------------------
 if __name__ == '__main__': LdapTester().test()
diff --git a/bin/eggify.py b/bin/eggify.py
index a99e425..1fcc16e 100644
--- a/bin/eggify.py
+++ b/bin/eggify.py
@@ -110,12 +110,12 @@ class EggifyScript:
         eggFullName = j(self.eggFolder, self.eggName)
         if os.path.exists(eggFullName):
             os.remove(eggFullName)
-            print('Existing "%s" was removed.' % eggFullName)
+            print(('Existing "%s" was removed.' % eggFullName))
         # Create a temp folder where to store the egg
         eggTempFolder = os.path.splitext(eggFullName)[0]
         if os.path.exists(eggTempFolder):
             FolderDeleter.delete(eggTempFolder)
-            print('Removed "%s" that was in my way.' % eggTempFolder)
+            print(('Removed "%s" that was in my way.' % eggTempFolder))
         os.mkdir(eggTempFolder)
         # Create the "Products" sub-folder if we must wrap the package in this
         # namespace
@@ -170,7 +170,7 @@ class EggifyScript:
         try:
             self.checkArgs(options, args)
             self.eggify()
-        except EggifierError, ee:
+        except EggifierError as ee:
             sys.stderr.write(str(ee) + '\nRun eggify.py -h for getting help.\n')
             sys.exit(ERROR_CODE)
 
diff --git a/bin/generate.py b/bin/generate.py
index 0e5a28a..a08737f 100644
--- a/bin/generate.py
+++ b/bin/generate.py
@@ -41,7 +41,7 @@ class GeneratorScript:
             sys.exit(ERROR_CODE)
         # Check existence of application
         if not os.path.exists(args[0]):
-            print(APP_NOT_FOUND % args[0])
+            print((APP_NOT_FOUND % args[0]))
             sys.exit(ERROR_CODE)
         # Convert app path to an absolute path
         args[0] = os.path.abspath(args[0])
@@ -55,8 +55,8 @@ class GeneratorScript:
         (options, args) = optParser.parse_args()
         try:
             self.manageArgs(optParser, options, args)
-            print('Appy version: %s' % appy.version.verbose)
-            print('Generating Zope product in %s/zope...' % args[0])
+            print(('Appy version: %s' % appy.version.verbose))
+            print(('Generating Zope product in %s/zope...' % args[0]))
             ZopeGenerator(args[0], options).run()
             # Give the user some statistics about its code
             LinesCounter(args[0], excludes=['%szope' % os.sep]).run()
@@ -71,7 +71,7 @@ class GeneratorScript:
                 f.close()
                 version = version[:version.find('build')-1]
                 Debianizer(app, appDir, appVersion=version).run()
-        except GeneratorError, ge:
+        except GeneratorError as ge:
             sys.stderr.write(str(ge))
             sys.stderr.write('\n')
             optParser.print_help()
diff --git a/bin/job.py b/bin/job.py
index f308925..4dca931 100644
--- a/bin/job.py
+++ b/bin/job.py
@@ -82,6 +82,6 @@ else:
                 targetObject = getattr(targetObject, elem)
         # Execute the method on the target object
         if args: args = args.split('*')
-        exec 'targetObject.%s(*args)' % toolMethod
+        exec('targetObject.%s(*args)' % toolMethod)
     transaction.commit()
 # ------------------------------------------------------------------------------
diff --git a/bin/new.py b/bin/new.py
index 7700f15..f74767c 100644
--- a/bin/new.py
+++ b/bin/new.py
@@ -106,17 +106,17 @@ class ZopeInstanceCreator:
         f = file('bin/zopectl', 'w')
         f.write(zopeCtl % self.instancePath)
         f.close()
-        os.chmod('bin/zopectl', 0744) # Make it executable by owner.
+        os.chmod('bin/zopectl', 0o744) # Make it executable by owner.
         # Create bin/runzope
         f = file('bin/runzope', 'w')
         f.write(runZope % self.instancePath)
         f.close()
-        os.chmod('bin/runzope', 0744) # Make it executable by owner.
+        os.chmod('bin/runzope', 0o744) # Make it executable by owner.
         # Create bin/startoo
         f = file('bin/startoo', 'w')
         f.write(ooStart)
         f.close()
-        os.chmod('bin/startoo', 0744) # Make it executable by owner.
+        os.chmod('bin/startoo', 0o744) # Make it executable by owner.
         # Create etc/zope.conf
         os.mkdir('etc')
         f = file('etc/zope.conf', 'w')
@@ -138,10 +138,10 @@ class ZopeInstanceCreator:
         password = binascii.b2a_base64(sha('admin').digest())[:-1]
         f.write('admin:{SHA}%s\n' % password)
         f.close()
-        os.chmod('inituser', 0644)
+        os.chmod('inituser', 0o644)
         # User "zope" must own this instance
         os.system('chown -R zope %s' % self.instancePath)
-        print('Zope instance created in %s.' % self.instancePath)
+        print(('Zope instance created in %s.' % self.instancePath))
         os.chdir(curdir)
 
 # ------------------------------------------------------------------------------
@@ -229,7 +229,7 @@ class NewScript:
         j = os.path.join
         # As eggs have been deleted, versions of components are lost. Reify
         # them from p_versions.
-        dVersions = ['"%s":"%s"' % (n, v) for n, v in versions.iteritems()]
+        dVersions = ['"%s":"%s"' % (n, v) for n, v in versions.items()]
         sVersions = 'appyVersions = {' + ','.join(dVersions) + '}'
         codeFile = "%s/pkg_resources.py" % self.libFolder
         f = file(codeFile)
@@ -326,7 +326,7 @@ class NewScript:
         action = 'Copying'
         if linksForProducts:
             action = 'Symlinking'
-        print('%s Plone stuff in the Zope instance...' % action)
+        print(('%s Plone stuff in the Zope instance...' % action))
         if self.ploneVersion in ('plone25', 'plone30'):
             self.installPlone25or30Stuff(linksForProducts)
         elif self.ploneVersion in ('plone3x', 'plone4'):
@@ -379,11 +379,11 @@ class NewScript:
         try:
             self.manageArgs(args)
             if self.ploneVersion != 'zope':
-                print('Creating new %s instance...' % self.ploneVersion)
+                print(('Creating new %s instance...' % self.ploneVersion))
                 self.createInstance(linksForProducts)
             else:
                 ZopeInstanceCreator(self.instancePath).run()
-        except NewError, ne:
+        except NewError as ne:
             optParser.print_help()
             sys.stderr.write(str(ne))
             sys.stderr.write('\n')
diff --git a/bin/odfgrep.py b/bin/odfgrep.py
index 4320acf..af00819 100644
--- a/bin/odfgrep.py
+++ b/bin/odfgrep.py
@@ -52,7 +52,7 @@ class OdfGrep:
         # Run "grep" in this folder
         match = self.callGrep(tempFolder)
         if match:
-            print('Found in %s' % fileName)
+            print(('Found in %s' % fileName))
         FolderDeleter.delete(tempFolder)
 
     def run(self):
@@ -65,7 +65,7 @@ class OdfGrep:
                     if os.path.splitext(name)[1] in self.toUnzip:
                         self.grepFile(os.path.join(dir, name))
         else:
-            print('%s does not exist.' % self.fileOrFolder)
+            print(('%s does not exist.' % self.fileOrFolder))
 
 # ------------------------------------------------------------------------------
 if __name__ == '__main__':
diff --git a/bin/publish.py b/bin/publish.py
index a86bd66..ba9ecad 100644
--- a/bin/publish.py
+++ b/bin/publish.py
@@ -85,8 +85,8 @@ class FtpFolder:
     def clean(self, site):
         '''Cleans this folder'''
         # First, clean subFolders if they exist
-        print('Cleaning %s %d subFolders' % \
-              (self.getFullName(), len(self.subFolders)))
+        print(('Cleaning %s %d subFolders' % \
+              (self.getFullName(), len(self.subFolders))))
         for subFolder in self.subFolders:
             subFolder.clean(site)
             # Remove the subFolder
@@ -95,7 +95,7 @@ class FtpFolder:
         for f in self.files:
             fileName = '%s/%s' % (self.getFullName(), f)
             site.delete(fileName)
-            print('%s removed.' % fileName)
+            print(('%s removed.' % fileName))
 
 # ------------------------------------------------------------------------------
 class AppySite:
@@ -148,11 +148,11 @@ class AppySite:
         fileExt = os.path.splitext(fileName)[1]
         if fileExt in self.textExtensions:
             # Make a transfer in text mode
-            print('Transfer file %s (text mode)' % fileName)
+            print(('Transfer file %s (text mode)' % fileName))
             self.site.storlines(cmd, localFile)
         else:
             # Make a transfer in binary mode
-            print('Transfer file %s (binary mode)' % fileName)
+            print(('Transfer file %s (binary mode)' % fileName))
             self.site.storbinary(cmd, localFile)
 
     def publish(self):
@@ -257,7 +257,7 @@ class Publisher:
             yesNo = '[Y/n]'
         else:
             yesNo = '[y/N]'
-        print(question + ' ' + yesNo + ' ')
+        print((question + ' ' + yesNo + ' '))
         response = sys.stdin.readline().strip().lower()
         res = False
         if response in ('y', 'yes'):
@@ -274,7 +274,7 @@ class Publisher:
 
     def executeCommand(self, cmd):
         '''Executes the system command p_cmd.'''
-        print('Executing %s...' % cmd)
+        print(('Executing %s...' % cmd))
         os.system(cmd)
 
     distExcluded = ('appy/doc', 'appy/temp', 'appy/versions', 'appy/gen/test')
@@ -340,7 +340,7 @@ class Publisher:
                                     newZipRelease, default='yes'):
                 print('Publication canceled.')
                 sys.exit(1)
-            print('Removing obsolete %s...' % newZipRelease)
+            print(('Removing obsolete %s...' % newZipRelease))
             os.remove(newZipRelease)
         zipFile = zipfile.ZipFile(newZipRelease, 'w', zipfile.ZIP_DEFLATED)
         curdir = os.getcwd()
@@ -474,7 +474,7 @@ class Publisher:
         if minimalist:
             FolderDeleter.delete('%s/pod/test' % genSrcFolder)
         # Write the appy version into the code itself (in appy/version.py)'''
-        print('Publishing version %s...' % self.versionShort)
+        print(('Publishing version %s...' % self.versionShort))
         # Dump version info in appy/version.py
         f = file('%s/version.py' % genSrcFolder, 'w')
         f.write('short = "%s"\n' % self.versionShort)
@@ -495,7 +495,7 @@ class Publisher:
         Cleaner().run(verbose=False)
         # Perform a small analysis on the Appy code
         LinesCounter(appy).run()
-        print('Generating site in %s...' % self.genFolder)
+        print(('Generating site in %s...' % self.genFolder))
         minimalist = self.askQuestion('Minimalist (shipped without tests)?',
                                       default='no')
         self.prepareGenFolder(minimalist)
diff --git a/bin/restore.py b/bin/restore.py
index f77fcad..b8fb343 100644
--- a/bin/restore.py
+++ b/bin/restore.py
@@ -21,10 +21,10 @@ class ZodbRestorer:
             datePart = '-D %s' % self.restoreDate
         repozoCmd = '%s %s -Rv -r %s %s -o %s' % (self.python,
             self.repozo, self.backupFolder, datePart, self.storageLocation)
-        print('Executing %s...' % repozoCmd)
+        print(('Executing %s...' % repozoCmd))
         os.system(repozoCmd)
         stopTime = time.time()
-        print('Done in %d minute(s).' % ((stopTime-startTime)/60))
+        print(('Done in %d minute(s).' % ((stopTime-startTime)/60)))
 
 # ------------------------------------------------------------------------------
 class ZodbRestoreScript:
@@ -56,7 +56,7 @@ class ZodbRestoreScript:
             f.write('Hello.')
             f.close()
             os.remove(args[0])
-        except OSError, oe:
+        except OSError as oe:
             raise RestoreError('I do not have the right to write file ' \
                                '"%s".' % args[0])
 
@@ -81,7 +81,7 @@ class ZodbRestoreScript:
             self.checkArgs(options, args)
             backuper = ZodbRestorer(args[0], args[1], options)
             backuper.run()
-        except RestoreError, be:
+        except RestoreError as be:
             sys.stderr.write(str(be))
             sys.stderr.write('\n')
             optParser.print_help()
diff --git a/bin/zip.py b/bin/zip.py
index 49cb810..5feb399 100644
--- a/bin/zip.py
+++ b/bin/zip.py
@@ -8,29 +8,29 @@ class Zipper:
     def __init__(self):
         self.zipFileName = '%s/Desktop/appy.zip' % os.environ['HOME']
     def createZipFile(self):
-        print('Creating %s...' % self.zipFileName)
+        print(('Creating %s...' % self.zipFileName))
         zipFile = zipfile.ZipFile(self.zipFileName, 'w', zipfile.ZIP_DEFLATED)
         for dir, dirnames, filenames in os.walk(appyPath):
             for f in filenames:
                 fileName = os.path.join(dir, f)
                 arcName = fileName[fileName.find('appy/'):]
-                print('Adding %s' % fileName)
+                print(('Adding %s' % fileName))
                 zipFile.write(fileName, arcName)
         zipFile.close()
 
     def run(self):
         # Where to put the zip file ?
-        print("Where do you want to put appy.zip ? [Default is %s] " % \
-              os.path.dirname(self.zipFileName))
+        print(("Where do you want to put appy.zip ? [Default is %s] " % \
+              os.path.dirname(self.zipFileName)))
         response = sys.stdin.readline().strip()
         if response:
             if os.path.exists(response) and os.path.isdir(response):
                 self.zipFileName = '%s/appy.zip' % response
             else:
-                print('%s is not a folder.' % response)
+                print(('%s is not a folder.' % response))
                 sys.exit(1)
         if os.path.exists(self.zipFileName):
-            print('Removing existing %s...' % self.zipFileName)
+            print(('Removing existing %s...' % self.zipFileName))
             os.remove(self.zipFileName)
         Cleaner().run(verbose=False)
         self.createZipFile()
diff --git a/fields/__init__.py b/fields/__init__.py
index e72f422..b254f2a 100644
--- a/fields/__init__.py
+++ b/fields/__init__.py
@@ -21,9 +21,9 @@ from appy.gen.layout import Table, defaultFieldLayouts
 from appy.gen import utils as gutils
 from appy.px import Px
 from appy.shared import utils as sutils
-from group import Group
-from search import Search
-from page import Page
+from .group import Group
+from .page import Page
+import collections
 
 # In this file, names "list" and "dict" refer to sub-modules. To use Python
 # builtin types, use __builtins__['list'] and __builtins__['dict']
@@ -370,7 +370,7 @@ class Field:
         labelName = name
         trPrefix = None
         if self.label:
-            if isinstance(self.label, basestring): trPrefix = self.label
+            if isinstance(self.label, str): trPrefix = self.label
             else: # It is a tuple (trPrefix, name)
                 if self.label[1]: labelName = self.label[1]
                 if self.label[0]: trPrefix = self.label[0]
@@ -382,16 +382,16 @@ class Field:
         self.helpId  = self.labelId + '_help'
         # Determine read and write permissions for this field
         rp = self.specificReadPermission
-        if rp and not isinstance(rp, basestring):
+        if rp and not isinstance(rp, str):
             self.readPermission = '%s: Read %s %s' % (appName, prefix, name)
-        elif rp and isinstance(rp, basestring):
+        elif rp and isinstance(rp, str):
             self.readPermission = rp
         else:
             self.readPermission = 'read'
         wp = self.specificWritePermission
-        if wp and not isinstance(wp, basestring):
+        if wp and not isinstance(wp, str):
             self.writePermission = '%s: Write %s %s' % (appName, prefix, name)
-        elif wp and isinstance(wp, basestring):
+        elif wp and isinstance(wp, str):
             self.writePermission = wp
         else:
             self.writePermission = 'write'
@@ -442,7 +442,7 @@ class Field:
                                           self.readPermission
         if not obj.allows(perm): return
         # Evaluate self.show
-        if callable(self.show):
+        if isinstance(self.show, collections.Callable):
             res = self.callMethod(obj, self.show)
         else:
             res = self.show
@@ -480,7 +480,7 @@ class Field:
         if not masterData: return True
         else:
             master, masterValue = masterData
-            if masterValue and callable(masterValue): return True
+            if masterValue and isinstance(masterValue, collections.Callable): return True
             reqValue = master.getRequestValue(obj)
             # reqValue can be a list or not
             if type(reqValue) not in sutils.sequenceTypes:
@@ -496,8 +496,8 @@ class Field:
         if isinstance(mapping, __builtins__['dict']):
             # Is it a dict like {'label':..., 'descr':...}, or is it directly a
             # dict with a mapping?
-            for k, v in mapping.iteritems():
-                if (k not in self.labelTypes) or isinstance(v, basestring):
+            for k, v in mapping.items():
+                if (k not in self.labelTypes) or isinstance(v, str):
                     # It is already a mapping
                     return {'label':mapping, 'descr':mapping, 'help':mapping}
             # If we are here, we have {'label':..., 'descr':...}. Complete
@@ -520,7 +520,7 @@ class Field:
             areDefault = True
             layouts = self.computeDefaultLayouts()
         else:
-            if isinstance(layouts, basestring):
+            if isinstance(layouts, str):
                 # The user specified a single layoutString (the "edit" one)
                 layouts = {'edit': layouts}
             elif isinstance(layouts, Table):
@@ -541,8 +541,8 @@ class Field:
         # We have now a dict of layouts in p_layouts. Ensure now that a Table
         # instance is created for every layout (=value from the dict). Indeed,
         # a layout could have been expressed as a simple layout string.
-        for layoutType in layouts.iterkeys():
-            if isinstance(layouts[layoutType], basestring):
+        for layoutType in layouts.keys():
+            if isinstance(layouts[layoutType], str):
                 layouts[layoutType] = Table(layouts[layoutType])
         # Derive "view", "search" and "cell" layouts from the "edit" layout
         # when relevant.
@@ -566,11 +566,11 @@ class Field:
         if areDefault and not self.group and \
            not ((self.type == 'String') and (self.format == self.XHTML)) and \
            not (self.type == 'Ref'):
-            for layoutType in layouts.iterkeys():
+            for layoutType in layouts.keys():
                 layouts[layoutType].width = ''
         # Remove letters "r" from the layouts if the field is not required.
         if not self.required:
-            for layoutType in layouts.iterkeys():
+            for layoutType in layouts.keys():
                 layouts[layoutType].removeElement('r')
         # Derive some boolean values from the layouts.
         self.hasLabel = self.hasLayoutElement('l', layouts)
@@ -597,7 +597,7 @@ class Field:
     def hasLayoutElement(self, element, layouts):
         '''This method returns True if the given layout p_element can be found
            at least once among the various p_layouts defined for this field.'''
-        for layout in layouts.itervalues():
+        for layout in layouts.values():
             if element in layout.layoutString: return True
         return False
 
@@ -610,7 +610,7 @@ class Field:
         '''Gets, as a string, the layouts as could have been specified as input
            value for the Field constructor.'''
         res = '{'
-        for k, v in self.layouts.iteritems():
+        for k, v in self.layouts.items():
             res += '"%s":"%s",' % (k, v.layoutString)
         res += '}'
         return res
@@ -650,7 +650,7 @@ class Field:
         if self.isEmptyValue(obj, value):
             # If there is no value, get the default value if any: return
             # self.default, of self.default() if it is a method.
-            if callable(self.default):
+            if isinstance(self.default, collections.Callable):
                 try:
                     # Caching a default value can lead to problems. For example,
                     # the process of creating an object from another one, or
@@ -660,7 +660,7 @@ class Field:
                     # but it they depend on values set at (b), and are cached
                     # and indexed, (c) will get the wrong, cached value.
                     return self.callMethod(obj, self.default, cache=False)
-                except Exception, e:
+                except Exception as e:
                     # Already logged. Here I do not raise the exception,
                     # because it can be raised as the result of reindexing
                     # the object in situations that are not foreseen by
@@ -723,12 +723,13 @@ class Field:
         # Start by getting the field value on p_obj
         res = self.getValue(obj)
         # Zope catalog does not like unicode strings
-        if isinstance(res, unicode): res = res.encode('utf-8')
+        if isinstance(value, str):
+            res = value.encode('utf-8')
         if forSearch and (res != None):
             if type(res) in sutils.sequenceTypes:
                 vals = []
                 for v in res:
-                    if isinstance(v, unicode): vals.append(v.encode('utf-8'))
+                    if isinstance(v, str): vals.append(v.encode('utf-8'))
                     else: vals.append(str(v))
                 res = ' '.join(vals)
             else:
@@ -824,7 +825,7 @@ class Field:
            this field is the slave of another field.'''
         if not self.master: return ''
         res = 'slave*%s*' % self.masterName
-        if not callable(self.masterValue):
+        if not isinstance(self.masterValue, collections.Callable):
             res += '*'.join(self.masterValue)
         else:
             res += '+'
@@ -866,7 +867,7 @@ class Field:
     def securityCheck(self, obj, value):
         '''This method performs some security checks on the p_value that
            represents user input.'''
-        if not isinstance(value, basestring): return
+        if not isinstance(value, str): return
         # Search Javascript code in the value (prevent XSS attacks).
         if '<script' in value:
             obj.log('Detected Javascript in user input.', type='error')
@@ -900,14 +901,14 @@ class Field:
                 # It is a custom function: execute it
                 try:
                     validValue = self.validator(obj, value)
-                    if isinstance(validValue, basestring) and validValue:
+                    if isinstance(validValue, str) and validValue:
                         # Validation failed; and p_validValue contains an error
                         # message.
                         return validValue
                     else:
                         if not validValue:
                             return obj.translate('field_invalid')
-                except Exception, e:
+                except Exception as e:
                     return str(e)
                 except:
                     return obj.translate('field_invalid')
@@ -931,7 +932,7 @@ class Field:
         obj = obj.appy()
         try:
             return gutils.callMethod(obj, method, cache=cache)
-        except TypeError, te:
+        except TypeError as te:
             # Try a version of the method that would accept self as an
             # additional parameter. In this case, we do not try to cache the
             # value (we do not call gutils.callMethod), because the value may
@@ -939,11 +940,11 @@ class Field:
             tb = sutils.Traceback.get()
             try:
                 return method(obj, self)
-            except Exception, e:
+            except Exception as e:
                 obj.log(tb, type='error')
                 # Raise the initial error.
                 raise te
-        except Exception, e:
+        except Exception as e:
             obj.log(sutils.Traceback.get(), type='error')
             raise e
 
@@ -951,7 +952,7 @@ class Field:
         '''Gets the value of attribue p_name on p_self, which can be a simple
            value or the result of a method call on p_obj.'''
         res = getattr(self, name)
-        if not callable(res): return res
+        if not isinstance(res, collections.Callable): return res
         return self.callMethod(obj, res)
 
     def process(self, obj):
diff --git a/fields/boolean.py b/fields/boolean.py
index ebbcc30..83b851d 100644
--- a/fields/boolean.py
+++ b/fields/boolean.py
@@ -123,7 +123,7 @@ class Boolean(Field):
 
     def getStorableValue(self, obj, value):
         if not self.isEmptyValue(obj, value):
-            exec 'res = %s' % value
+            exec('res = %s' % value)
             return res
 
     def isTrue(self, obj, dbValue):
@@ -131,7 +131,7 @@ class Boolean(Field):
            not?'''
         rq = obj.REQUEST
         # Get the value we must compare (from request or from database)
-        if rq.has_key(self.name):
+        if self.name in rq:
             return rq.get(self.name) in ('True', 1, '1')
         return dbValue
 # ------------------------------------------------------------------------------
diff --git a/fields/calendar.py b/fields/calendar.py
index 12c2a74..551037d 100644
--- a/fields/calendar.py
+++ b/fields/calendar.py
@@ -1263,20 +1263,20 @@ class Calendar(Field):
             maxDay = (maxYear, maxDate.month(), maxDate.day())
         # Browse years
         years = getattr(obj, self.name)
-        for year in years.keys():
+        for year in list(years.keys()):
             # Don't take this year into account if outside interval
             if minDate and (year < minYear): continue
             if maxDate and (year > maxYear): continue
             months = years[year]
             # Browse this year's months
-            for month in months.keys():
+            for month in list(months.keys()):
                 # Don't take this month into account if outside interval
                 thisMonth = (year, month)
                 if minDate and (thisMonth < minMonth): continue
                 if maxDate and (thisMonth > maxMonth): continue
                 days = months[month]
                 # Browse this month's days
-                for day in days.keys():
+                for day in list(days.keys()):
                     # Don't take this day into account if outside interval
                     thisDay = (year, month, day)
                     if minDate and (thisDay < minDay): continue
diff --git a/fields/computed.py b/fields/computed.py
index 3a7d48e..376e411 100644
--- a/fields/computed.py
+++ b/fields/computed.py
@@ -47,7 +47,7 @@ class Computed(Field):
         # the user interface while m_method computes the value stored in the
         # catalog.
         self.formatMethod = formatMethod
-        if isinstance(self.method, basestring):
+        if isinstance(self.method, str):
             # A legacy macro identifier. Raise an exception
             raise Exception(self.WRONG_METHOD % self.method)
         # Does field computation produce plain text or XHTML?
@@ -99,6 +99,6 @@ class Computed(Field):
             res = self.formatMethod(obj, value)
         else:
             res = value
-        if not isinstance(res, basestring): res = str(res)
+        if not isinstance(res, str): res = str(res)
         return res
 # ------------------------------------------------------------------------------
diff --git a/fields/date.py b/fields/date.py
index 75001c4..4393c2d 100644
--- a/fields/date.py
+++ b/fields/date.py
@@ -219,7 +219,7 @@ class Date(Field):
 
     def getSelectableYears(self):
         '''Gets the list of years one may select for this field.'''
-        res = range(self.startYear, self.endYear + 1)
+        res = list(range(self.startYear, self.endYear + 1))
         if self.reverseYears: res.reverse()
         return res
 
@@ -227,7 +227,7 @@ class Date(Field):
         DateTime = obj.getProductConfig().DateTime
         try:
             value = DateTime(value)
-        except DateTime.DateError, ValueError:
+        except DateTime.DateError as ValueError:
             return obj.translate('bad_date')
 
     def getFormattedValue(self, obj, value, layoutType='view',
@@ -278,7 +278,7 @@ class Date(Field):
         # Get the value we must compare (from request or from database)
         rq = obj.REQUEST
         partName = '%s_%s' % (self.name, fieldPart)
-        if rq.has_key(partName):
+        if partName in rq:
             compValue = rq.get(partName)
             if compValue.isdigit():
                 compValue = int(compValue)
diff --git a/fields/file.py b/fields/file.py
index a9a09a3..f255647 100644
--- a/fields/file.py
+++ b/fields/file.py
@@ -108,7 +108,7 @@ class FileInfo:
         '''Removes the file from the filesystem.'''
         try:
             os.remove(osPathJoin(dbFolder, self.fsPath, self.fsName))
-        except Exception, e:
+        except Exception as e:
             # If the current ZODB transaction is re-triggered, the file may
             # already have been deleted.
             pass
@@ -207,10 +207,10 @@ class FileInfo:
             if fileObj.data.__class__.__name__ == 'Pdata':
                 # The file content is splitted in several chunks
                 f.write(fileObj.data.data)
-                nextPart = fileObj.data.next
+                nextPart = fileObj.data.__next__
                 while nextPart:
                     f.write(nextPart.data)
-                    nextPart = nextPart.next
+                    nextPart = nextPart.__next__
             else:
                 # Only one chunk
                 f.write(fileObj.data)
@@ -393,7 +393,7 @@ class File(Field):
     def validateValue(self, obj, value):
         form = obj.REQUEST.form
         action = '%s_delete' % self.name
-        if (not value or not value.filename) and form.has_key(action) and \
+        if (not value or not value.filename) and action in form and \
             not form[action]:
             # If this key is present but empty, it means that the user selected
             # "replace the file with a new one". So in this case he must provide
@@ -450,7 +450,7 @@ class File(Field):
                 # Case c
                 fileInfo = (value.name, value.content, value.mimeType)
                 info.writeFile(self.name, fileInfo, dbFolder)
-            elif isinstance(value, basestring):
+            elif isinstance(value, str):
                 # Case d
                 info.copyFile(self.name, value, dbFolder)
             elif isinstance(value, FileInfo):
diff --git a/fields/group.py b/fields/group.py
index 540f2b2..bedf94e 100644
--- a/fields/group.py
+++ b/fields/group.py
@@ -40,7 +40,7 @@ class Group:
         # which will be used for HTML param "width".
         if wide == True:
             self.wide = '100%'
-        elif isinstance(wide, basestring):
+        elif isinstance(wide, str):
             self.wide = wide
         else:
             self.wide = ''
@@ -106,7 +106,7 @@ class Group:
            can be a string or a Group instance; this method returns always a
            Group instance.'''
         res = groupData
-        if res and isinstance(res, basestring):
+        if res and isinstance(res, str):
             # Group data is given as a string. 2 more possibilities:
             # (a) groupData is simply the name of the group;
             # (b) groupData is of the form <groupName>_<numberOfColumns>.
@@ -336,7 +336,7 @@ class UiGroup:
         # All p_group attributes become self attributes. This is required
         # because a UiGroup, in some PXs, must behave like a Field (ie, have
         # the same attributes, like "master".
-        for name, value in group.__dict__.iteritems():
+        for name, value in group.__dict__.items():
             if not name.startswith('_'):
                 setattr(self, name, value)
         self.group = group
@@ -346,7 +346,7 @@ class UiGroup:
         labelName = self.name
         prefix = className
         if group.label:
-            if isinstance(group.label, basestring): prefix = group.label
+            if isinstance(group.label, str): prefix = group.label
             else: # It is a tuple (className, name)
                 if group.label[1]: labelName = group.label[1]
                 if group.label[0]: prefix = group.label[0]
diff --git a/fields/integer.py b/fields/integer.py
index 7369b89..bb8110f 100644
--- a/fields/integer.py
+++ b/fields/integer.py
@@ -60,7 +60,7 @@ class Integer(Field):
                        height, maxChars, colspan, master, masterValue, focus,
                        historized, mapping, label, sdefault, scolspan, swidth,
                        sheight, persist, view, xml)
-        self.pythonType = long
+        self.pythonType = int
 
     def validateValue(self, obj, value):
         try:
diff --git a/fields/list.py b/fields/list.py
index 48dda1d..494cc82 100644
--- a/fields/list.py
+++ b/fields/list.py
@@ -132,7 +132,7 @@ class List(Field):
         name = requestName or self.name # A List may be into another List (?)
         prefix = name + '*' + self.fields[0][0] + '*'
         res = {}
-        for key in request.keys():
+        for key in list(request.keys()):
             if not key.startswith(prefix): continue
             # I have found a row. Gets its index.
             row = Object()
@@ -145,7 +145,7 @@ class List(Field):
                 setattr(row, subName, v)
             res[rowIndex] = row
         # Produce a sorted list
-        keys = res.keys()
+        keys = list(res.keys())
         keys.sort()
         res = [res[key] for key in keys]
         # I store in the request this computed value. This way, when individual
diff --git a/fields/ogone.py b/fields/ogone.py
index af589cb..28b1a5b 100644
--- a/fields/ogone.py
+++ b/fields/ogone.py
@@ -83,13 +83,13 @@ class Ogone(Field):
         # Create a new dict by removing p_keysToIgnore from p_values, and by
         # upperizing all keys.
         shaRes = {}
-        for k, v in values.iteritems():
+        for k, v in values.items():
             if k in keysToIgnore: continue
             # Ogone: we must not include empty values.
             if (v == None) or (v == ''): continue
             shaRes[k.upper()] = v
         # Create a sorted list of keys
-        keys = shaRes.keys()
+        keys = list(shaRes.keys())
         keys.sort()
         shaList = []
         for k in keys:
@@ -127,7 +127,7 @@ class Ogone(Field):
         # Ogone's response.
         res['paramplus'] = 'name=%s' % self.name
         # Ensure every value is a str
-        for k in res.iterkeys():
+        for k in res.keys():
             if not isinstance(res[k], str):
                 res[k] = str(res[k])
         # Compute a SHA-1 key as required by Ogone and add it to the res
@@ -154,7 +154,7 @@ class Ogone(Field):
                             'administrator has been contacted.')
         # Create a nice object from the form.
         response = Object()
-        for k, v in obj.REQUEST.form.iteritems():
+        for k, v in obj.REQUEST.form.items():
             setattr(response, k, v)
         # Call the field method that handles the response received from Ogone.
         url = self.responseMethod(obj.appy(), response)
diff --git a/fields/page.py b/fields/page.py
index aac6feb..ba53d02 100644
--- a/fields/page.py
+++ b/fields/page.py
@@ -16,6 +16,7 @@
 
 # ------------------------------------------------------------------------------
 from appy import Object
+import collections
 
 # ------------------------------------------------------------------------------
 class Page:
@@ -53,7 +54,7 @@ class Page:
            (c) a Page instance.
            This method returns always a Page instance.'''
         res = pageData
-        if res and isinstance(res, basestring):
+        if res and isinstance(res, str):
             # Page data is given as a string.
             pageElems = pageData.rsplit('_', 1)
             if len(pageElems) == 1: # We have case (a)
diff --git a/fields/pod.py b/fields/pod.py
index 8112de3..4e8106e 100644
--- a/fields/pod.py
+++ b/fields/pod.py
@@ -16,7 +16,7 @@
 
 # ------------------------------------------------------------------------------
 import time, os, os.path
-from file import FileInfo
+from .file import FileInfo
 from appy import Object
 from appy.fields import Field
 from appy.px import Px
@@ -25,6 +25,7 @@ from appy.gen import utils as gutils
 from appy.pod import PodError
 from appy.pod.renderer import Renderer
 from appy.shared import utils as sutils
+import collections
 
 # ------------------------------------------------------------------------------
 class Mailing:
@@ -170,7 +171,7 @@ class Pod(Field):
         # of your app will be referred as "Test.odt" in self.template. If it is
         # stored within sub-folder "pod", it will be referred as "pod/Test.odt".
         if not template: raise Exception(Pod.NO_TEMPLATE)
-        if isinstance(template, basestring):
+        if isinstance(template, str):
             self.template = [template]
         elif isinstance(template, tuple):
             self.template = list(template)
@@ -396,7 +397,7 @@ class Pod(Field):
                 formats = self.showTemplate(obj, template)
                 if not formats: continue
                 elif isinstance(formats, bool): formats = self.formats
-                elif isinstance(formats, basestring): formats = (formats,)
+                elif isinstance(formats, str): formats = (formats,)
                 res.append(Object(template=template, formats=formats,
                            freezeFormats=self.getFreezeFormats(obj, template)))
         return res
@@ -525,7 +526,7 @@ class Pod(Field):
         templatePath = self.getTemplatePath(diskFolder, template)
         # Get or compute the specific POD context
         specificContext = None
-        if callable(self.context):
+        if isinstance(self.context, collections.Callable):
             specificContext = self.callMethod(obj, self.context)
         else:
             specificContext = self.context
@@ -544,7 +545,7 @@ class Pod(Field):
             # Retrieve query params
             cmd = ', '.join(Pod.queryParams)
             cmd += " = queryData.split(';')"
-            exec cmd
+            exec(cmd)
             # (re-)execute the query, but without any limit on the number of
             # results; return Appy objects.
             objs = tool.o.executeQuery(obj.o.portal_type, searchName=search,
@@ -559,7 +560,7 @@ class Pod(Field):
         # when generating frozen documents).
         if '_checked' not in podContext: podContext['_checked'] = Object()
         # Define a potential global styles mapping
-        if callable(self.stylesMapping):
+        if isinstance(self.stylesMapping, collections.Callable):
             stylesMapping = self.callMethod(obj, self.stylesMapping)
         else:
             stylesMapping = self.stylesMapping
@@ -575,7 +576,7 @@ class Pod(Field):
         try:
             renderer = Renderer(**rendererParams)
             renderer.run()
-        except PodError, pe:
+        except PodError as pe:
             if not os.path.exists(result):
                 # In some (most?) cases, when OO returns an error, the result is
                 # nevertheless generated.
@@ -643,7 +644,7 @@ class Pod(Field):
             # Generate the document
             doc = self.getValue(obj, template=template, format=format,
                                 result=result)
-            if isinstance(doc, basestring):
+            if isinstance(doc, str):
                 # An error occurred, the document was not generated.
                 obj.log(self.FREEZE_ERROR % (format, self.name, doc),
                         type='error')
@@ -658,7 +659,7 @@ class Pod(Field):
                     obj.log('freeze: overwriting %s...' % result)
                 doc = self.getValue(obj, template=template, format='odt',
                                     result=result)
-                if isinstance(doc, basestring):
+                if isinstance(doc, str):
                     self.log(self.FREEZE_ERROR % ('odt', self.name, doc),
                              type='error')
                     raise Exception(self.FREEZE_FATAL_ERROR)
@@ -762,7 +763,7 @@ class Pod(Field):
             res = self.getValue(obj, template=template, format=format,
                                 queryData=rq.get('queryData'),
                                 customContext=self.getCustomContext(obj, rq))
-            if isinstance(res, basestring):
+            if isinstance(res, str):
                 # An error has occurred, and p_res contains the error message
                 obj.say(res)
                 return tool.goto(rq.get('HTTP_REFERER'))
diff --git a/fields/ref.py b/fields/ref.py
index 7735200..480575b 100644
--- a/fields/ref.py
+++ b/fields/ref.py
@@ -23,6 +23,7 @@ from appy.px import Px
 from appy.gen.layout import Table
 from appy.gen import utils as gutils
 from appy.shared import utils as sutils
+import collections
 
 # ------------------------------------------------------------------------------
 class Ref(Field):
@@ -826,7 +827,7 @@ class Ref(Field):
             # If this field is an ajax-updatable slave, no need to compute
             # possible values: it will be overridden by method self.masterValue
             # by a subsequent ajax request (=the "if" statement above).
-            if self.masterValue and callable(self.masterValue):
+            if self.masterValue and isinstance(self.masterValue, collections.Callable):
                 objects = []
             else:
                 if not self.select:
@@ -921,7 +922,7 @@ class Ref(Field):
         res = self.getAttribute(obj, 'numbered')
         if not res: return res
         # Returns the column width.
-        if not isinstance(res, basestring): return '15px'
+        if not isinstance(res, str): return '15px'
         return res
 
     def getMenuUrl(self, zobj, tied):
@@ -996,14 +997,14 @@ class Ref(Field):
         # Also ensure that multiplicities are enforced.
         if not value:
             nbOfRefs = 0
-        elif isinstance(value, basestring):
+        elif isinstance(value, str):
             nbOfRefs = 1
         else:
             nbOfRefs = len(value)
         minRef = self.multiplicity[0]
         maxRef = self.multiplicity[1]
         if maxRef == None:
-            maxRef = sys.maxint
+            maxRef = sys.maxsize
         if nbOfRefs < minRef:
             return obj.translate('min_ref_violated')
         elif nbOfRefs > maxRef:
@@ -1119,7 +1120,7 @@ class Ref(Field):
         if type(objects) not in sutils.sequenceTypes: objects = [objects]
         tool = obj.getTool()
         for i in range(len(objects)):
-            if isinstance(objects[i], basestring):
+            if isinstance(objects[i], str):
                 # We have an UID here
                 objects[i] = tool.getObject(objects[i], appy=True)
             else:
diff --git a/fields/search.py b/fields/search.py
index 91c1be4..4260fb3 100644
--- a/fields/search.py
+++ b/fields/search.py
@@ -19,7 +19,7 @@ from appy.px import Px
 from appy.gen import utils as gutils
 from appy.gen.indexer import defaultIndexes
 from appy.shared import utils as sutils
-from group import Group
+from .group import Group
 
 # ------------------------------------------------------------------------------
 class Search:
@@ -85,12 +85,12 @@ class Search:
            (fieldName == 'SearchableText'):
             # For TextIndex indexes. We must split p_fieldValue into keywords.
             res = gutils.Keywords(fieldValue).get()
-        elif isinstance(fieldValue, basestring) and fieldValue.endswith('*'):
+        elif isinstance(fieldValue, str) and fieldValue.endswith('*'):
             v = fieldValue[:-1]
             # Warning: 'z' is higher than 'Z'!
             res = {'query':(v,v+'z'), 'range':'min:max'}
         elif type(fieldValue) in sutils.sequenceTypes:
-            if fieldValue and isinstance(fieldValue[0], basestring):
+            if fieldValue and isinstance(fieldValue[0], str):
                 # We have a list of string values (ie: we need to
                 # search v1 or v2 or...)
                 res = fieldValue
@@ -118,7 +118,7 @@ class Search:
            sortBy and sortOrder (and not "resolve" them to Zope's sort_on and
            sort_order).'''
         # Put search criteria in p_criteria
-        for name, value in self.fields.iteritems():
+        for name, value in self.fields.items():
             # Management of searches restricted to objects linked through a
             # Ref field: not implemented yet.
             if name == '_ref': continue
diff --git a/fields/string.py b/fields/string.py
index 1bbc56c..685274c 100644
--- a/fields/string.py
+++ b/fields/string.py
@@ -25,6 +25,7 @@ from appy.shared.data import countries
 from appy.shared.xml_parser import XhtmlCleaner
 from appy.shared.diff import HtmlDiff
 from appy.shared import utils as sutils
+import collections
 
 # ------------------------------------------------------------------------------
 digit  = re.compile('[0-9]')
@@ -471,7 +472,7 @@ class String(Field):
         res = True
         if type(self.validator) in (list, tuple):
             for elem in self.validator:
-                if not isinstance(elem, basestring):
+                if not isinstance(elem, str):
                     res = False
                     break
         else:
@@ -533,7 +534,7 @@ class String(Field):
         if not value:
             if self.isMultiValued(): return emptyTuple
             else: return value
-        if isinstance(value, basestring) and self.isMultiValued():
+        if isinstance(value, str) and self.isMultiValued():
             value = [value]
         elif isinstance(value, tuple):
             value = list(value)
@@ -602,8 +603,7 @@ class String(Field):
            identifies the language-specific part we will work on.'''
         res = None
         lastEvent = None
-        name = language and ('%s-%s' % (self.name, language)) or self.name
-        for event in obj.workflow_history['appy']:
+        for event in obj.workflow_history.values()[0]:
             if event['action'] != '_datachange_': continue
             if name not in event['changes']: continue
             if res == None:
@@ -660,7 +660,7 @@ class String(Field):
                 res = obj.formatText(res, format='html')
         # If value starts with a carriage return, add a space; else, it will
         # be ignored.
-        if isinstance(res, basestring) and \
+        if isinstance(res, str) and \
            (res.startswith('\n') or res.startswith('\r\n')): res = ' ' + res
         return res
 
@@ -774,7 +774,7 @@ class String(Field):
             # If this field is an ajax-updatable slave, no need to compute
             # possible values: it will be overridden by method self.masterValue
             # by a subsequent ajax request (=the "if" statement above).
-            if self.masterValue and callable(self.masterValue) and \
+            if self.masterValue and isinstance(self.masterValue, collections.Callable) and \
                not ignoreMasterValues: return []
             if isinstance(self.validator, Selection):
                 # We need to call self.methodName for getting the (dynamic)
@@ -808,9 +808,9 @@ class String(Field):
                             obj = brains[0].getObject()
                 # Do we need to call the method on the object or on the wrapper?
                 if methodName.startswith('_appy_'):
-                    exec 'res = obj.%s(*args)' % methodName
+                    exec('res = obj.%s(*args)' % methodName)
                 else:
-                    exec 'res = obj.appy().%s(*args)' % methodName
+                    exec('res = obj.appy().%s(*args)' % methodName)
                 if not withTranslations: res = [v[0] for v in res]
                 elif isinstance(res, list): res = res[:]
             else:
@@ -847,7 +847,7 @@ class String(Field):
         elif self.isSelect:
             # Check that the value is among possible values
             possibleValues = self.getPossibleValues(obj,ignoreMasterValues=True)
-            if isinstance(value, basestring):
+            if isinstance(value, str):
                 error = value not in possibleValues
             else:
                 error = False
@@ -872,7 +872,7 @@ class String(Field):
         return value
 
     def getUnilingualStorableValue(self, obj, value):
-        isString = isinstance(value, basestring)
+        isString = isinstance(value, str)
         isEmpty = Field.isEmptyValue(self, obj, value)
         # Apply transform if required
         if isString and not isEmpty and (self.transform != 'none'):
@@ -1021,7 +1021,7 @@ class String(Field):
         if self.allowImageUpload:
             ckAttrs['filebrowserUploadUrl'] = '%s/upload' % obj.absolute_url()
         ck = []
-        for k, v in ckAttrs.iteritems():
+        for k, v in ckAttrs.items():
             if isinstance(v, int): sv = str(v)
             if isinstance(v, bool): sv = str(v).lower()
             else: sv = '"%s"' % v
@@ -1059,7 +1059,7 @@ class String(Field):
            name containing a row number from a field within a list field.'''
         rq = obj.REQUEST
         # Get the value we must compare (from request or from database)
-        if rq.has_key(fieldName):
+        if fieldName in rq:
             compValue = rq.get(fieldName)
         else:
             compValue = dbValue
diff --git a/fields/workflow.py b/fields/workflow.py
index bd539e9..258f629 100644
--- a/fields/workflow.py
+++ b/fields/workflow.py
@@ -14,10 +14,12 @@
 # You should have received a copy of the GNU General Public License along with
 # Appy. If not, see <http://www.gnu.org/licenses/>.
 # ------------------------------------------------------------------------------
-import types, string
-from group import Group
+import types
+import .string
+from .group import Group
 from appy.px import Px
 from appy.gen.utils import User
+import collections
 
 # Default Appy permissions -----------------------------------------------------
 r, w, d = ('read', 'write', 'delete')
@@ -73,7 +75,7 @@ class State:
            exists, or creates a Role instance, puts it in self.usedRoles and
            returns it else. If it is a Role instance, the method stores it in
            self.usedRoles if it is not in it yet and returns it.'''
-        if isinstance(role, basestring):
+        if isinstance(role, str):
             if role in self.usedRoles:
                 return self.usedRoles[role]
             else:
@@ -88,24 +90,24 @@ class State:
     def standardizeRoles(self):
         '''This method converts, within self.permissions, every role to a
            Role instance. Every used role is stored in self.usedRoles.'''
-        for permission, roles in self.permissions.iteritems():
+        for permission, roles in self.permissions.items():
             if not roles: continue # Nobody may have this permission
-            if isinstance(roles, basestring) or isinstance(roles, Role):
+            if isinstance(roles, str) or isinstance(roles, Role):
                 self.permissions[permission] = [self.getRole(roles)]
             elif isinstance(roles, list):
                 for i in range(len(roles)): roles[i] = self.getRole(roles[i])
             else: # A tuple
                 self.permissions[permission] = [self.getRole(r) for r in roles]
 
-    def getUsedRoles(self): return self.usedRoles.values()
+    def getUsedRoles(self): return list(self.usedRoles.values())
 
     def addRoles(self, roleNames, permissions=()):
         '''Adds p_roleNames in self.permissions. If p_permissions is specified,
            roles are added to those permissions only. Else, roles are added for
            every permission within self.permissions.'''
-        if isinstance(roleNames, basestring): roleNames = (roleNames,)
-        if isinstance(permissions, basestring): permissions = (permissions,)
-        for perm, roles in self.permissions.iteritems():
+        if isinstance(roleNames, str): roleNames = (roleNames,)
+        if isinstance(permissions, str): permissions = (permissions,)
+        for perm, roles in self.permissions.items():
             if permissions and (perm not in permissions): continue
             for roleName in roleNames:
                 # Do nothing if p_roleName is already almong roles.
@@ -124,9 +126,9 @@ class State:
         '''Removes p_roleNames within dict self.permissions. If p_permissions is
            specified, removal is restricted to those permissions. Else, removal
            occurs throughout the whole dict self.permissions.'''
-        if isinstance(roleNames, basestring): roleNames = (roleNames,)
-        if isinstance(permissions, basestring): permissions = (permissions,)
-        for perm, roles in self.permissions.iteritems():
+        if isinstance(roleNames, str): roleNames = (roleNames,)
+        if isinstance(permissions, str): permissions = (permissions,)
+        for perm, roles in self.permissions.items():
             if permissions and (perm not in permissions): continue
             for roleName in roleNames:
                 # Remove this role if present in roles for this permission.
@@ -138,9 +140,9 @@ class State:
     def setRoles(self, roleNames, permissions=()):
         '''Sets p_rolesNames for p_permissions if not empty, for every
            permission in self.permissions else.'''
-        if isinstance(roleNames, basestring): roleNames = (roleNames,)
-        if isinstance(permissions, basestring): permissions = (permissions,)
-        for perm in self.permissions.iterkeys():
+        if isinstance(roleNames, str): roleNames = (roleNames,)
+        if isinstance(permissions, str): permissions = (permissions,)
+        for perm in self.permissions.keys():
             if permissions and (perm not in permissions): continue
             roles = self.permissions[perm] = []
             for roleName in roleNames:
@@ -150,8 +152,8 @@ class State:
         '''Replaces p_oldRoleName by p_newRoleName. If p_permissions is
            specified, the replacement is restricted to those permissions. Else,
            replacements apply to the whole dict self.permissions.'''
-        if isinstance(permissions, basestring): permissions = (permissions,)
-        for perm, roles in self.permissions.iteritems():
+        if isinstance(permissions, str): permissions = (permissions,)
+        for perm, roles in self.permissions.items():
             if permissions and (perm not in permissions): continue
             # Find and delete p_oldRoleName
             for role in roles:
@@ -170,7 +172,7 @@ class State:
            worklflow, this method will always return True (I mean: in this case,
            having an isolated state does not mean the state has been
            deactivated).'''
-        for tr in wf.__dict__.itervalues():
+        for tr in wf.__dict__.values():
             if not isinstance(tr, Transition): continue
             if not tr.hasState(self, True): continue
             # Transition "tr" has this state as start state. If the end state is
@@ -200,7 +202,7 @@ class Transition:
         # be useful for "undo" transitions, for example.
         self.states = self.standardiseStates(states)
         self.condition = condition
-        if isinstance(condition, basestring):
+        if isinstance(condition, str):
             # The condition specifies the name of a role.
             self.condition = Role(condition)
         self.action = action
@@ -276,7 +278,7 @@ class Transition:
 
     def isShowable(self, workflow, obj):
         '''Is this transition showable?'''
-        if callable(self.show):
+        if isinstance(self.show, collections.Callable):
             return self.show(workflow, obj.appy())
         else:
             return self.show
@@ -330,7 +332,7 @@ class Transition:
             for condition in self.condition:
                 # "Unwrap" role names from Role instances
                 if isinstance(condition, Role): condition = condition.name
-                if isinstance(condition, basestring): # It is a role
+                if isinstance(condition, str): # It is a role
                     if hasRole == None:
                         hasRole = False
                     if user.has_role(condition, obj):
@@ -450,7 +452,7 @@ class Transition:
         transition = getattr(workflow, transition)
         # Browse all transitions and find the one starting at p_transition's end
         # state and coming back to p_transition's start state.
-        for trName, tr in workflow.__dict__.iteritems():
+        for trName, tr in workflow.__dict__.items():
             if not isinstance(tr, Transition) or (tr == transition): continue
             if transition.isSingle():
                 if tr.hasState(transition.states[1], True) and \
diff --git a/gen/descriptors.py b/gen/descriptors.py
index a1a73d1..f289a13 100644
--- a/gen/descriptors.py
+++ b/gen/descriptors.py
@@ -5,9 +5,9 @@
 # ------------------------------------------------------------------------------
 import types, copy
 import appy.gen as gen
-import po
-from model import ModelClass
-from utils import produceNiceMessage, getClassName
+from . import po
+from .model import ModelClass
+from .utils import produceNiceMessage, getClassName
 TABS = 4 # Number of blanks in a Python indentation.
 
 # ------------------------------------------------------------------------------
@@ -130,7 +130,7 @@ class ClassDescriptor(Descriptor):
     def isAbstract(self):
         '''Is self.klass abstract?'''
         res = False
-        if self.klass.__dict__.has_key('abstract'):
+        if 'abstract' in self.klass.__dict__:
             res = self.klass.__dict__['abstract']
         return res
 
@@ -139,7 +139,7 @@ class ClassDescriptor(Descriptor):
            concept into the application. For example, creating instances
            of such classes will be easy from the user interface.'''
         res = False
-        if self.klass.__dict__.has_key('root'):
+        if 'root' in self.klass.__dict__:
             res = self.klass.__dict__['root']
         return res
 
@@ -150,7 +150,7 @@ class ClassDescriptor(Descriptor):
         theClass = self.klass
         if klass:
             theClass = klass
-        if theClass.__dict__.has_key('folder'):
+        if 'folder' in theClass.__dict__:
             res = theClass.__dict__['folder']
         else:
             if theClass.__bases__:
@@ -176,14 +176,14 @@ class ClassDescriptor(Descriptor):
     def getCreateMean(self, type='Import'):
         '''Returns the mean for this class that corresponds to p_type, or
            None if the class does not support this create mean.'''
-        if not self.klass.__dict__.has_key('create'): return
+        if 'create' not in self.klass.__dict__: return
         else:
             means = self.klass.create
             if not means: return
             if not isinstance(means, tuple) and not isinstance(means, list):
                 means = [means]
             for mean in means:
-                exec 'found = isinstance(mean, %s)' % type
+                exec('found = isinstance(mean, %s)' % type)
                 if found: return mean
 
     @staticmethod
@@ -192,7 +192,7 @@ class ClassDescriptor(Descriptor):
            p_tool is given, we are at execution time (not a generation time),
            and we may potentially execute search.show methods that allow to
            conditionnaly include a search or not.'''
-        if klass.__dict__.has_key('search'):
+        if 'search' in klass.__dict__:
             searches = klass.__dict__['search']
             if not tool: return searches
             # Evaluate attributes "show" for every search.
@@ -229,10 +229,10 @@ class ClassDescriptor(Descriptor):
 
     def addField(self, fieldName, fieldType):
         '''Adds a new field to the Tool.'''
-        exec "self.modelClass.%s = fieldType" % fieldName
+        exec("self.modelClass.%s = fieldType" % fieldName)
         if fieldName in self.modelClass._appy_attributes:
-            print('Warning, field "%s" is already existing on class "%s"' % \
-                  (fieldName, self.modelClass.__name__))
+            print(('Warning, field "%s" is already existing on class "%s"' % \
+                  (fieldName, self.modelClass.__name__)))
             return
         self.modelClass._appy_attributes.append(fieldName)
         self.orderedAttributes.append(fieldName)
@@ -488,9 +488,9 @@ class TranslationClassDescriptor(ClassDescriptor):
         maxLine = 100 # We suppose a line is 100 characters long.
         width = 0
         height = 0
-        for fileName, poFile in i18nFiles.iteritems():
+        for fileName, poFile in i18nFiles.items():
             if not fileName.startswith('%s-' % appName) or \
-               not i18nFiles[fileName].messagesDict.has_key(messageId):
+               messageId not in i18nFiles[fileName].messagesDict:
                 # In this case this is not one of our Appy-managed translation
                 # files.
                 continue
diff --git a/gen/generator.py b/gen/generator.py
index 0923c9e..0b4c09c 100644
--- a/gen/generator.py
+++ b/gen/generator.py
@@ -3,10 +3,11 @@ import os, os.path, re, sys, parser, symbol, token, types
 import appy, appy.pod.renderer
 from appy.shared.utils import FolderDeleter
 import appy.gen as gen
-import po
-from descriptors import *
-from utils import getClassName
-from model import ModelClass, User, Group, Tool, Translation, Page
+from . import po
+from .descriptors import *
+from .utils import getClassName
+from .model import ModelClass, User, Group, Tool, Translation, Page
+import collections
 
 # ------------------------------------------------------------------------------
 class GeneratorError(Exception): pass
@@ -160,7 +161,7 @@ class Generator:
            appy.fields.Field, it will be considered a gen-class. If p_klass
            declares at least one static attribute that is a appy.gen.State,
            it will be considered a gen-workflow.'''
-        for attr in klass.__dict__.itervalues():
+        for attr in klass.__dict__.values():
             if isinstance(attr, gen.Field): return 'class'
             elif isinstance(attr, gen.State): return 'workflow'
 
@@ -173,11 +174,11 @@ class Generator:
             self.totalNumberOfTests += 1
             res = True
         # Count also docstring in methods
-        if type(moduleOrClass) == types.ClassType:
-            for name, elem in moduleOrClass.__dict__.iteritems():
+        if type(moduleOrClass) == type:
+            for name, elem in moduleOrClass.__dict__.items():
                 if type(elem) in (staticmethod, classmethod):
                     elem = elem.__get__(name)
-                if callable(elem) and (type(elem) != types.ClassType) and \
+                if isinstance(elem, collections.Callable) and (type(elem) != type) and \
                    hasattr(elem, '__doc__') and elem.__doc__ and \
                    (elem.__doc__.find('>>>') != -1):
                     res = True
@@ -198,8 +199,8 @@ class Generator:
             self.modulesWithTests.add(module.__name__)
         classType = type(Generator)
         # Find all classes in this module
-        for name in module.__dict__.keys():
-            exec 'moduleElem = module.%s' % name
+        for name in list(module.__dict__.keys()):
+            exec('moduleElem = module.%s' % name)
             # Ignore non-classes module elements or classes that were imported
             # from other modules.
             if (type(moduleElem) != classType) or  \
@@ -213,7 +214,7 @@ class Generator:
             # Collect non-parsable attrs = back references added
             # programmatically
             moreAttrs = []
-            for eName, eValue in moduleElem.__dict__.iteritems():
+            for eName, eValue in moduleElem.__dict__.items():
                 if isinstance(eValue, gen.Field) and (eName not in attrs):
                     moreAttrs.append(eName)
             # Sort them in alphabetical order: else, order would be random
@@ -257,7 +258,7 @@ class Generator:
         # What is the name of the application ?
         appName = os.path.basename(self.application)
         # Get the app-specific config if any
-        exec 'import %s as appModule' % appName
+        exec('import %s as appModule' % appName)
         if hasattr (appModule, 'Config'):
             self.config = appModule.Config
             if not issubclass(self.config, gen.Config):
@@ -273,7 +274,7 @@ class Generator:
             # Ignore non Python files
             if not fileName.endswith('.py'): continue
             moduleName = '%s.%s' % (appName, os.path.splitext(fileName)[0])
-            exec 'import %s' % moduleName
+            exec('import %s' % moduleName)
             modules.append(eval(moduleName))
         # Parse imported modules
         for module in modules:
@@ -321,7 +322,7 @@ class Generator:
             fileContent = f.read()
             f.close()
             if not fileName.endswith('.png'):
-                for rKey, rValue in replacements.iteritems():
+                for rKey, rValue in replacements.items():
                     fileContent = fileContent.replace(
                         '<!%s!>' % rKey, str(rValue))
             f = file(resultPath, 'w')
@@ -343,7 +344,7 @@ class Generator:
         msg = ''
         if self.totalNumberOfTests:
             msg = ' (number of tests found: %d)' % self.totalNumberOfTests
-        print('Done%s.' % msg)
+        print(('Done%s.' % msg))
 
 # ------------------------------------------------------------------------------
 class ZopeGenerator(Generator):
@@ -413,7 +414,7 @@ class ZopeGenerator(Generator):
             f.close()
         # Generate i18n pot file
         potFileName = '%s.pot' % self.applicationName
-        if self.i18nFiles.has_key(potFileName):
+        if potFileName in self.i18nFiles:
             potFile = self.i18nFiles[potFileName]
         else:
             fullName = os.path.join(self.application, 'tr', potFileName)
@@ -427,14 +428,14 @@ class ZopeGenerator(Generator):
             self.options.i18nClean, keepExistingOrder=False)
         potFile.generate()
         if removedLabels:
-            print('Warning: %d messages were removed from translation ' \
-                  'files: %s' % (len(removedLabels), str(removedLabels)))
+            print(('Warning: %d messages were removed from translation ' \
+                  'files: %s' % (len(removedLabels), str(removedLabels))))
         # Generate i18n po files
         for language in self.config.languages:
             # I must generate (or update) a po file for the language(s)
             # specified in the configuration.
             poFileName = potFile.getPoFileName(language)
-            if self.i18nFiles.has_key(poFileName):
+            if poFileName in self.i18nFiles:
                 poFile = self.i18nFiles[poFileName]
             else:
                 fullName = os.path.join(self.application, 'tr', poFileName)
@@ -501,7 +502,7 @@ class ZopeGenerator(Generator):
             for role in creators:
                 if role.name not in allRoles:
                     allRoles[role.name] = role
-        res = allRoles.values()
+        res = list(allRoles.values())
         # Filter the result according to parameters
         for p in ('appy', 'local', 'grantable'):
             if eval(p) != None:
@@ -621,12 +622,12 @@ class ZopeGenerator(Generator):
             else:
                 # If a child of this class is already present, we must insert
                 # this klass before it.
-                lowestChildIndex = sys.maxint
+                lowestChildIndex = sys.maxsize
                 for resClass in resClasses:
                     if klass in resClass.__bases__:
                         lowestChildIndex = min(lowestChildIndex,
                                                resClasses.index(resClass))
-                if lowestChildIndex != sys.maxint:
+                if lowestChildIndex != sys.maxsize:
                     res.insert(lowestChildIndex, classDescr)
                     resClasses.insert(lowestChildIndex, klass)
                 else:
@@ -745,7 +746,7 @@ class ZopeGenerator(Generator):
         '''Is called each time an Appy class is found in the application, for
            generating the corresponding Archetype class.'''
         k = classDescr.klass
-        print('Generating %s.%s (gen-class)...' % (k.__module__, k.__name__))
+        print(('Generating %s.%s (gen-class)...' % (k.__module__, k.__name__)))
         # Determine base Zope class
         isFolder = classDescr.isFolder()
         baseClass = isFolder and 'Folder' or 'SimpleItem'
@@ -772,7 +773,7 @@ class ZopeGenerator(Generator):
         '''This method creates the i18n labels related to the workflow described
            by p_wfDescr.'''
         k = wfDescr.klass
-        print('Generating %s.%s (gen-workflow)...' % (k.__module__, k.__name__))
+        print(('Generating %s.%s (gen-workflow)...' % (k.__module__, k.__name__)))
         # Identify workflow name
         wfName = WorkflowDescriptor.getWorkflowName(wfDescr.klass)
         # Add i18n messages for states
diff --git a/gen/indexer.py b/gen/indexer.py
index 05436a2..d54317d 100644
--- a/gen/indexer.py
+++ b/gen/indexer.py
@@ -33,7 +33,7 @@ def updateIndexes(installer, indexInfo):
     '''This function updates the indexes defined in the catalog.'''
     catalog = installer.app.catalog
     logger = installer.logger
-    for indexName, indexType in indexInfo.iteritems():
+    for indexName, indexType in indexInfo.items():
         indexRealType = indexType
         if indexType in ('XhtmlIndex', 'TextIndex', 'ListIndex'):
             indexRealType = 'ZCTextIndex'
diff --git a/gen/installer.py b/gen/installer.py
index 52a672e..13f25c3 100644
--- a/gen/installer.py
+++ b/gen/installer.py
@@ -43,7 +43,7 @@ class FakeZCatalog:
 def onDelSession(sessionObject, container):
     '''This function is called when a session expires.'''
     rq = container.REQUEST
-    if rq.cookies.has_key('_appy_') and rq.cookies.has_key('_ZopeId') and \
+    if '_appy_' in rq.cookies and '_ZopeId' in rq.cookies and \
        (rq['_ZopeId'] == sessionObject.token):
         # The request comes from a guy whose session has expired.
         resp = rq.RESPONSE
@@ -155,7 +155,7 @@ class ZopeInstaller:
         # Create or update Appy-wide indexes and field-related indexes
         indexInfo = defaultIndexes.copy()
         tool = self.app.config
-        for className in self.config.attributes.iterkeys():
+        for className in self.config.attributes.keys():
             wrapperClass = tool.getAppyClass(className, wrapper=True)
             indexInfo.update(wrapperClass.getIndexes(includeDefaults=False))
         updateIndexes(self, indexInfo)
@@ -196,7 +196,7 @@ class ZopeInstaller:
         if hasattr(appyTool, 'beforeInstall'): appyTool.beforeInstall()
 
         # Create the default users if they do not exist.
-        for login, roles in self.defaultUsers.iteritems():
+        for login, roles in self.defaultUsers.items():
             if not appyTool.count('User', noSecurity=True, login=login):
                 appyTool.create('users', noSecurity=True, id=login, login=login,
                                 password3=login, password4=login,
@@ -277,7 +277,7 @@ class ZopeInstaller:
             name = klass.__name__
             module = klass.__module__
             wrapper = klass.wrapperClass
-            exec 'from %s import manage_add%s as ctor' % (module, name)
+            exec('from %s import manage_add%s as ctor' % (module, name))
             self.zopeContext.registerClass(meta_type=name,
                 constructors = (ctor,), permission = None)
             # Create workflow prototypical instances in __instance__ attributes
@@ -316,7 +316,7 @@ class ZopeInstaller:
             # Post-initialise every Appy type
             for baseClass in klass.wrapperClass.__bases__:
                 if baseClass.__name__ == 'AbstractWrapper': continue
-                for name, appyType in baseClass.__dict__.iteritems():
+                for name, appyType in baseClass.__dict__.items():
                     if not isinstance(appyType, gen.Field) or \
                            (isinstance(appyType, gen.Ref) and appyType.isBack):
                         continue # Back refs are initialised within fw refs
diff --git a/gen/layout.py b/gen/layout.py
index 46263f5..e2caa51 100644
--- a/gen/layout.py
+++ b/gen/layout.py
@@ -39,9 +39,9 @@
 
 # ------------------------------------------------------------------------------
 rowDelimiters =  {'-':'middle', '=':'top', '_':'bottom'}
-rowDelms = ''.join(rowDelimiters.keys())
+rowDelms = ''.join(list(rowDelimiters.keys()))
 cellDelimiters = {'|': 'center', ';': 'left', '!': 'right'}
-cellDelms = ''.join(cellDelimiters.keys())
+cellDelms = ''.join(list(cellDelimiters.keys()))
 
 pxDict = {
   # Page-related elements
@@ -138,7 +138,7 @@ class Table:
         # Initialise simple params, either from the true params, either from
         # the p_other Table instance.
         for param in Table.simpleParams:
-            exec 'self.%s = %s%s' % (param, source, param)
+            exec('self.%s = %s%s' % (param, source, param))
         # The following attribute will store a special Row instance used for
         # defining column properties.
         self.headerRow = None
diff --git a/gen/mail.py b/gen/mail.py
index 08f3ac9..c223d60 100644
--- a/gen/mail.py
+++ b/gen/mail.py
@@ -120,10 +120,10 @@ def sendMail(config, to, subject, body, attachments=None, log=None):
         if res and log:
             log('could not send mail to some recipients. %s' % str(res),
                 type='warning')
-    except smtplib.SMTPException, e:
+    except smtplib.SMTPException as e:
         if log:
             log('%s: mail sending failed (%s)' % (config, str(e)), type='error')
-    except socket.error, se:
+    except socket.error as se:
         if log:
             log('%s: mail sending failed (%s)' % (config, str(se)),type='error')
 # ------------------------------------------------------------------------------
diff --git a/gen/migrator.py b/gen/migrator.py
index 967e701..0fc3829 100644
--- a/gen/migrator.py
+++ b/gen/migrator.py
@@ -38,10 +38,10 @@ class Migrator:
                     if frozen.data.__class__.__name__ == 'Pdata':
                         # The file content is splitted in several chunks.
                         f.write(frozen.data.data)
-                        nextPart = frozen.data.next
+                        nextPart = frozen.data.__next__
                         while nextPart:
                             f.write(nextPart.data)
-                            nextPart = nextPart.next
+                            nextPart = nextPart.__next__
                     else:
                         # Only one chunk
                         f.write(frozen.data)
diff --git a/gen/mixins/TestMixin.py b/gen/mixins/TestMixin.py
index aefe1f2..7ad0ba0 100644
--- a/gen/mixins/TestMixin.py
+++ b/gen/mixins/TestMixin.py
@@ -13,18 +13,18 @@ class TestMixin:
         '''Returns the list of sub-modules of p_app that are non-empty.'''
         res = []
         try:
-            exec 'import %s' % moduleName
-            exec 'moduleObj = %s' % moduleName
+            exec('import %s' % moduleName)
+            exec('moduleObj = %s' % moduleName)
             moduleFile = moduleObj.__file__
             if moduleFile.endswith('.pyc'):
                 moduleFile = moduleFile[:-1]
-        except ImportError, ie:
+        except ImportError as ie:
             return res
-        except SyntaxError, se:
+        except SyntaxError as se:
             return res
         # Include the module if not empty. "Emptyness" is determined by the
         # absence of names beginning with other chars than "__".
-        for elem in moduleObj.__dict__.iterkeys():
+        for elem in moduleObj.__dict__.keys():
             if not elem.startswith('__'):
                 res.append(moduleObj)
                 break
@@ -66,10 +66,10 @@ def afterTest(test):
     '''Is executed after every test.'''
     g = test.globs
     appName = g['tool'].o.getAppName()
-    exec 'from Products.%s import cov, covFolder, totalNumberOfTests, ' \
-         'countTest' % appName
+    exec('from Products.%s import cov, covFolder, totalNumberOfTests, ' \
+         'countTest' % appName)
     countTest()
-    exec 'from Products.%s import numberOfExecutedTests' % appName
+    exec('from Products.%s import numberOfExecutedTests' % appName)
     if cov and (numberOfExecutedTests == totalNumberOfTests):
         cov.stop()
         appModules = test.getNonEmptySubModules(appName)
diff --git a/gen/mixins/ToolMixin.py b/gen/mixins/ToolMixin.py
index 5b46e12..11bc99c 100644
--- a/gen/mixins/ToolMixin.py
+++ b/gen/mixins/ToolMixin.py
@@ -13,6 +13,7 @@ from appy.shared import mimeTypes
 from appy.shared import utils as sutils
 from appy.shared.data import languages
 from appy.shared.ldap_connector import LdapConnector
+import collections
 try:
     from AccessControl.ZopeSecurityPolicy import _noroles
 except ImportError:
@@ -36,7 +37,7 @@ class ToolMixin(BaseMixin):
            p_metaTypeOrAppyType.'''
         appName = self.getProductConfig().PROJECTNAME
         res = metaTypeOrAppyClass
-        if not isinstance(metaTypeOrAppyClass, basestring):
+        if not isinstance(metaTypeOrAppyClass, str):
             res = gutils.getClassName(metaTypeOrAppyClass, appName)
         if res.find('_wrappers') != -1:
             elems = res.split('_')
@@ -439,7 +440,7 @@ class ToolMixin(BaseMixin):
 
     def quote(self, s, escapeWithEntity=True):
         '''Returns the quoted version of p_s.'''
-        if not isinstance(s, basestring): s = str(s)
+        if not isinstance(s, str): s = str(s)
         repl = escapeWithEntity and '&apos;' or "\\'"
         s = s.replace('\r\n', '').replace('\n', '').replace("'", repl)
         return "'%s'" % s
@@ -452,7 +453,7 @@ class ToolMixin(BaseMixin):
 
     def getZopeClass(self, name):
         '''Returns the Zope class whose name is p_name.'''
-        exec 'from Products.%s.%s import %s as C'% (self.getAppName(),name,name)
+        exec('from Products.%s.%s import %s as C'% (self.getAppName(),name,name))
         return C
 
     def getAppyClass(self, zopeName, wrapper=False):
@@ -476,12 +477,12 @@ class ToolMixin(BaseMixin):
         '''Gets the different ways objects of p_klass can be created (currently:
            via a web form or programmatically only). Result is a list.'''
         res = []
-        if not klass.__dict__.has_key('create'):
+        if 'create' not in klass.__dict__:
             return ['form']
         else:
             means = klass.create
             if means:
-                if isinstance(means, basestring): res = [means]
+                if isinstance(means, str): res = [means]
                 else: res = means
         return res
 
@@ -511,7 +512,7 @@ class ToolMixin(BaseMixin):
         else:
             creators = self.getProductConfig().appConfig.defaultCreators
         # Resolve case (3): if "creators" is a method, execute it.
-        if callable(creators): creators = creators(self.appy())
+        if isinstance(creators, collections.Callable): creators = creators(self.appy())
         # Resolve case (2)
         if isinstance(creators, bool) or not creators: return creators
         # Resolve case (1): checks whether the user has at least one of the
@@ -595,7 +596,7 @@ class ToolMixin(BaseMixin):
         rq = self.REQUEST
         # Store the search criteria in the session
         criteria = self._getDefaultSearchCriteria()
-        for name in rq.form.keys():
+        for name in list(rq.form.keys()):
             if name.startswith('w_') and not self._searchValueIsEmpty(name):
                 hasStar = name.find('*') != -1
                 fieldName = not hasStar and name[2:] or name[2:name.find('*')]
@@ -609,17 +610,17 @@ class ToolMixin(BaseMixin):
                     # The type of the value is encoded after char "*".
                     name, type = name.split('*')
                     if type == 'bool':
-                        exec 'value = %s' % value
+                        exec('value = %s' % value)
                     elif type in ('int', 'float'):
                         # Get the "from" value
                         if not value: value = None
                         else:
-                            exec 'value = %s(value)' % type
+                            exec('value = %s(value)' % type)
                         # Get the "to" value
                         toValue = rq.form['%s_to' % name[2:]].strip()
                         if not toValue: toValue = None
                         else:
-                            exec 'toValue = %s(toValue)' % type
+                            exec('toValue = %s(toValue)' % type)
                         value = (value, toValue)
                     elif type == 'date':
                         prefix = name[2:]
@@ -640,8 +641,8 @@ class ToolMixin(BaseMixin):
                         if len(type) > 6:
                             transform = type.split('-')[1]
                             if (transform != 'none') and value:
-                                exec 'value = value.%s()' % \
-                                     self.transformMethods[transform]
+                                exec('value = value.%s()' % \
+                                     self.transformMethods[transform])
                 if isinstance(value, list):
                     # It is a list of values. Check if we have an operator for
                     # the field, to see if we make an "and" or "or" for all
@@ -697,7 +698,7 @@ class ToolMixin(BaseMixin):
            it among search criteria in the session.'''
         if not refInfo and (self.REQUEST.get('search', None) == 'customSearch'):
             criteria = self.REQUEST.SESSION.get('searchCriteria', None)
-            if criteria and criteria.has_key('_ref'): refInfo = criteria['_ref']
+            if criteria and '_ref' in criteria: refInfo = criteria['_ref']
         if not refInfo: return None, None
         objectUid, fieldName = refInfo.split(':')
         obj = self.getObject(objectUid)
@@ -856,7 +857,7 @@ class ToolMixin(BaseMixin):
                 try:
                     creds = creds.split(' ')[-1]
                     login, password = base64.decodestring(creds).split(':', 1)
-                except Exception, e:
+                except Exception as e:
                     pass
         # b. Identify the user from the authentication cookie.
         if not login:
@@ -968,7 +969,7 @@ class ToolMixin(BaseMixin):
         # Invalidate the user session.
         try:
             sdm = self.session_data_manager
-        except AttributeError, ae:
+        except AttributeError as ae:
             # When ran in test mode, session_data_manager is not there.
             sdm = None
         if sdm:
@@ -977,7 +978,7 @@ class ToolMixin(BaseMixin):
                 session.invalidate()
         self.log('logged out.')
         # Remove user from variable "loggedUsers"
-        if self.loggedUsers.has_key(userId): del self.loggedUsers[userId]
+        if userId in self.loggedUsers: del self.loggedUsers[userId]
         return self.goto(self.getApp().absolute_url())
 
     # This dict stores, for every logged user, the date/time of its last access
@@ -1247,7 +1248,7 @@ class ToolMixin(BaseMixin):
         if hasattr(klass, 'popup'):
             res.target = 'appyIFrame'
             d = klass.popup
-            if isinstance(d, basestring):
+            if isinstance(d, str):
                 # Width only
                 params = d[:-2]
             else:
diff --git a/gen/mixins/__init__.py b/gen/mixins/__init__.py
index 1a6e92b..9d87457 100644
--- a/gen/mixins/__init__.py
+++ b/gen/mixins/__init__.py
@@ -3,7 +3,7 @@
    - mixins/ToolMixin is mixed in with the generated application Tool class.'''
 
 # ------------------------------------------------------------------------------
-import os, os.path, re, sys, types, urllib, cgi
+import os, os.path, re, sys, types, urllib.request, urllib.parse, urllib.error, cgi
 from appy import Object
 from appy.px import Px
 from appy.fields.workflow import UiTransition
@@ -15,6 +15,7 @@ from appy.shared import utils as sutils
 from appy.shared.data import rtlLanguages
 from appy.shared.xml_parser import XmlMarshaller, XmlUnmarshaller
 from appy.shared.diff import HtmlDiff
+import collections
 
 # ------------------------------------------------------------------------------
 NUMBERED_ID = re.compile('.+\d{4}$')
@@ -371,9 +372,9 @@ class BaseMixin:
         # p_errors object. Within this object, for every error message that is
         # not a string, we replace it with the standard validation error for the
         # corresponding field.
-        for key, value in errors.__dict__.iteritems():
+        for key, value in errors.__dict__.items():
             resValue = value
-            if not isinstance(resValue, basestring):
+            if not isinstance(resValue, str):
                 resValue = self.translate('field_invalid')
             setattr(errors, key, resValue)
         return msg
@@ -419,7 +420,7 @@ class BaseMixin:
         # Trigger field-specific validation
         self.intraFieldValidation(errors, values)
         if errors.__dict__:
-            for k,v in errors.__dict__.iteritems(): rq.set('%s_error' % k, v)
+            for k,v in errors.__dict__.items(): rq.set('%s_error' % k, v)
             self.say(errorMessage)
             return self.gotoEdit()
 
@@ -427,7 +428,7 @@ class BaseMixin:
         msg = self.interFieldValidation(errors, values)
         if not msg: msg = errorMessage
         if errors.__dict__:
-            for k,v in errors.__dict__.iteritems(): rq.set('%s_error' % k, v)
+            for k,v in errors.__dict__.items(): rq.set('%s_error' % k, v)
             self.say(msg)
             return self.gotoEdit()
 
@@ -506,7 +507,7 @@ class BaseMixin:
                 # Get the list of indexes that apply on this object. Else, Zope
                 # will reindex all indexes defined in the catalog, and through
                 # acquisition, wrong methods can be called on wrong objects.
-                iNames = self.wrapperClass.getIndexes().keys()
+                iNames = list(self.wrapperClass.getIndexes().keys())
                 catalog.catalog_object(self, path, idxs=iNames)
 
     def xml(self, action=None):
@@ -529,14 +530,14 @@ class BaseMixin:
                 elif isinstance(methodRes, file):
                     res = methodRes.read()
                     methodRes.close()
-                elif isinstance(methodRes, basestring) and \
+                elif isinstance(methodRes, str) and \
                      methodRes.startswith('<?xml'): # Already XML
                     return methodRes
                 else:
                     marshaller = XmlMarshaller()
                     oType = isinstance(methodRes, Object) and 'popo' or 'appy'
                     res = marshaller.marshall(methodRes, objectType=oType)
-            except Exception, e:
+            except Exception as e:
                 tb = sutils.Traceback.get()
                 res = XmlMarshaller(rootTag='exception').marshall(tb)
                 self.log(tb, type='error')
@@ -548,7 +549,7 @@ class BaseMixin:
         '''Prints a p_msg in the user interface. p_logLevel may be "info",
            "warning" or "error".'''
         rq = self.REQUEST
-        if 'messages' not in rq.SESSION.keys():
+        if 'messages' not in list(rq.SESSION.keys()):
             plist = self.getProductConfig().PersistentList
             messages = rq.SESSION['messages'] = plist()
         else:
@@ -619,7 +620,7 @@ class BaseMixin:
            For a multilingual string field, p_changes can contain a key for
            every language, of the form <field name>-<language>.'''
         # Add to the p_changes dict the field labels
-        for name in changes.keys():
+        for name in list(changes.keys()):
             # "name" can contain the language for multilingual fields.
             if '-' in name:
                 fieldName, lg = name.split('-')
@@ -646,7 +647,7 @@ class BaseMixin:
            historized fields, while p_self already contains the (potentially)
            modified values.'''
         # Remove from previousData all values that were not changed
-        for name in previousData.keys():
+        for name in list(previousData.keys()):
             field = self.getAppyType(name)
             prev = previousData[name]
             curr = field.getValue(self)
@@ -655,7 +656,7 @@ class BaseMixin:
                    ((prev == '') and (curr == None)):
                     del previousData[name]
                     continue
-            except UnicodeDecodeError, ude:
+            except UnicodeDecodeError as ude:
                 # The string comparisons above may imply silent encoding-related
                 # conversions that may produce this exception.
                 continue
@@ -743,15 +744,15 @@ class BaseMixin:
         else:
             klass = self.appy().klass
             moduleName = klass.__module__
-            exec 'import %s' % moduleName
-            exec 'reload(%s)' % moduleName
-            exec 'res = %s.%s' % (moduleName, klass.__name__)
+            exec('import %s' % moduleName)
+            exec('reload(%s)' % moduleName)
+            exec('res = %s.%s' % (moduleName, klass.__name__))
             # More manipulations may have occurred in m_update
             if hasattr(res, 'update'):
                 parentName= res.__bases__[-1].__name__
                 moduleName= 'Products.%s.wrappers' % self.getTool().getAppName()
-                exec 'import %s' % moduleName
-                exec 'parent = %s.%s' % (moduleName, parentName)
+                exec('import %s' % moduleName)
+                exec('parent = %s.%s' % (moduleName, parentName))
                 res.update(parent)
             return res
 
@@ -839,15 +840,15 @@ class BaseMixin:
         req = self.REQUEST
         for field in self.getAllAppyTypes():
             if field.page.name != pageName: continue
-            if field.masterValue and callable(field.masterValue):
+            if field.masterValue and isinstance(field.masterValue, collections.Callable):
                 # We have a slave field that is updated via ajax requests.
                 name = field.name
                 # Remember the request value for this field if present.
-                if req.has_key(name) and req[name]:
+                if name in req and req[name]:
                     requestValues[name] = req[name]
                 # Remember the validation error for this field if present.
                 errorKey = '%s_error' % name
-                if req.has_key(errorKey):
+                if errorKey in req:
                     errors[name] = req[errorKey]
         return sutils.getStringDict(requestValues), sutils.getStringDict(errors)
 
@@ -899,7 +900,7 @@ class BaseMixin:
                 del phases[res[i].name]
                 del res[i]
         # Compute next/previous phases of every phase
-        for ph in phases.itervalues():
+        for ph in phases.values():
             ph.computeNextPrevious(res)
             ph.totalNbOfPhases = len(res)
         # Restrict the result to the current phase if required
@@ -1208,7 +1209,7 @@ class BaseMixin:
                 # fields' old values by their formatted counterparts.
                 event = history[i].copy()
                 event['changes'] = {}
-                for name, oldValue in history[i]['changes'].iteritems():
+                for name, oldValue in history[i]['changes'].items():
                     # "name" can specify a language-specific part in a
                     # multilingual field. "oldValue" is a tuple
                     # (value, fieldName).
@@ -1455,7 +1456,7 @@ class BaseMixin:
         # Add users or groups having, locally, this role on this object.
         localRoles = getattr(self.aq_base, '__ac_local_roles__', None)
         if not localRoles: return res
-        for id, roles in localRoles.iteritems():
+        for id, roles in localRoles.items():
             for role in roles:
                 if role in res:
                     usr = 'user:%s' % id
@@ -1465,7 +1466,7 @@ class BaseMixin:
     def showState(self):
         '''Must I show self's current state ?'''
         stateShow = self.State(name=False).show
-        if callable(stateShow):
+        if isinstance(stateShow, collections.Callable):
             return stateShow(self.getWorkflow(), self.appy())
         return stateShow
 
@@ -1479,7 +1480,7 @@ class BaseMixin:
         if not hasattr(klass, 'showTransitions'): return (layoutType=='view')
         showValue = klass.showTransitions
         # This value can be a single value or a tuple/list of values.
-        if isinstance(showValue, basestring): return layoutType == showValue
+        if isinstance(showValue, str): return layoutType == showValue
         return layoutType in showValue
 
     getUrlDefaults = {'page':True, 'nav':True}
@@ -1524,8 +1525,8 @@ class BaseMixin:
         if 'nav'  not in kwargs: kwargs['nav'] = True
         # Create URL parameters from kwargs
         params = []
-        for name, value in kwargs.iteritems():
-            if isinstance(value, basestring):
+        for name, value in kwargs.items():
+            if isinstance(value, str):
                 params.append('%s=%s' % (name, value))
             elif self.REQUEST.get(name, ''):
                 params.append('%s=%s' % (name, self.REQUEST[name]))
@@ -1601,7 +1602,7 @@ class BaseMixin:
             # Find the name of the method to call.
             methodName = rq.QUERY_STRING.split('=')[1]
             return self.xml(action=methodName)
-        elif rq.has_key('do'):
+        elif 'do' in rq:
             # The user wants to call a method on this object and get its result
             # as XML.
             return self.xml(action=rq['do'])
@@ -1672,7 +1673,7 @@ class BaseMixin:
             if field.type != 'group':
                 fieldMapping = field.mapping[label]
                 if fieldMapping:
-                    if callable(fieldMapping):
+                    if isinstance(fieldMapping, collections.Callable):
                         fieldMapping = field.callMethod(self, fieldMapping)
                     mapping.update(fieldMapping)
             label = getattr(field, '%sId' % label)
@@ -1697,15 +1698,15 @@ class BaseMixin:
             # Perform replacements, according to p_format.
             res = self.formatText(res, format)
             # Perform variable replacements
-            for name, repl in mapping.iteritems():
-                if not isinstance(repl, basestring): repl = str(repl)
+            for name, repl in mapping.items():
+                if not isinstance(repl, str): repl = str(repl)
                 res = res.replace('${%s}' % name, repl)
         return res
 
     def getPageLayout(self, layoutType):
         '''Returns the layout corresponding to p_layoutType for p_self.'''
         res = self.wrapperClass.getPageLayouts()[layoutType]
-        if isinstance(res, basestring): res = Table(res)
+        if isinstance(res, str): res = Table(res)
         return res
 
     def download(self, name=None):
diff --git a/gen/model.py b/gen/model.py
index 35082c9..814afeb 100644
--- a/gen/model.py
+++ b/gen/model.py
@@ -5,6 +5,7 @@
 # ------------------------------------------------------------------------------
 import types
 import appy.gen as gen
+import collections
 
 # Prototypical instances of every type -----------------------------------------
 class Protos:
@@ -49,7 +50,7 @@ class ModelClass:
         '''This method returns the code declaration for p_appyType.'''
         typeArgs = ''
         proto = Protos.get(appyType)
-        for name, value in appyType.__dict__.iteritems():
+        for name, value in appyType.__dict__.items():
             # Some attrs can't be given to the constructor
             if name in Protos.notInit: continue
             # If the given value corresponds to the default value, don't give it
@@ -74,7 +75,7 @@ class ModelClass:
                 # defined. So we initialize it to None. The post-init of the
                 # field must be done manually in wrappers.py.
                 value = 'None'
-            elif isinstance(value, basestring):
+            elif isinstance(value, str):
                 value = '"%s"' % value
             elif isinstance(value, gen.Ref):
                 if not value.isBack: continue
@@ -91,10 +92,10 @@ class ModelClass:
                 value = 'Grp("%s")' % value.name
             elif isinstance(value, gen.Page):
                 value = 'pges["%s"]' % value.name
-            elif callable(value):
+            elif isinstance(value, collections.Callable):
                 className = wrapperName
                 if (appyType.type == 'Ref') and appyType.isBack:
-                    className = value.im_class.__name__
+                    className = value.__self__.__class__.__name__
                 value = '%s.%s' % (className, value.__name__)
             typeArgs += '%s=%s,' % (name, value)
         return '%s(%s)' % (appyType.__class__.__name__, typeArgs)
@@ -118,17 +119,17 @@ class ModelClass:
         pages = {}
         layouts = []
         for name in klass._appy_attributes:
-            exec 'appyType = klass.%s' % name
+            exec('appyType = klass.%s' % name)
             if appyType.page.name not in pages:
                 pages[appyType.page.name] = appyType.page
         res += '    pges = {'
-        for page in pages.itervalues():
+        for page in pages.values():
             # Determine page "show" attributes
             pShow = ''
             for attr in ('',) + page.subElements:
                 attrName = 'show%s' % attr.capitalize()
                 pageShow = getattr(page, attrName)
-                if isinstance(pageShow, basestring): pageShow='"%s"' % pageShow
+                if isinstance(pageShow, str): pageShow='"%s"' % pageShow
                 elif callable(pageShow):
                     pageShow = '%s.%s' % (wrapperName, pageShow.__name__)
                 if pageShow != True:
@@ -142,7 +143,7 @@ class ModelClass:
         res += '}\n'
         # Secondly, dump every (not Ref.isBack) attribute
         for name in klass._appy_attributes:
-            exec 'appyType = klass.%s' % name
+            exec('appyType = klass.%s' % name)
             if (appyType.type == 'Ref') and appyType.isBack: continue
             typeBody = klass._appy_getTypeBody(appyType, wrapperName)
             res += '    %s=%s\n' % (name, typeBody)
@@ -305,12 +306,12 @@ class Tool(ModelClass):
     @classmethod
     def _appy_clean(klass):
         toClean = []
-        for k, v in klass.__dict__.iteritems():
+        for k, v in klass.__dict__.items():
             if not k.startswith('__') and (not k.startswith('_appy_')):
                 if k not in defaultToolFields:
                     toClean.append(k)
         for k in toClean:
-            exec 'del klass.%s' % k
+            exec('del klass.%s' % k)
         klass._appy_attributes = list(defaultToolFields)
         klass.folder = True
 # ------------------------------------------------------------------------------
diff --git a/gen/po.py b/gen/po.py
index 78ba3e3..54c73c5 100644
--- a/gen/po.py
+++ b/gen/po.py
@@ -1,6 +1,6 @@
 # ------------------------------------------------------------------------------
 import os, re, time, copy
-from utils import produceNiceMessage
+from .utils import produceNiceMessage
 
 # ------------------------------------------------------------------------------
 poHeader = '''msgid ""
@@ -213,7 +213,7 @@ class PoFile:
         if keepExistingOrder:
             # Update existing messages and add inexistent messages to the end.
             for newMsg in newMessages:
-                if self.messagesDict.has_key(newMsg.id):
+                if newMsg.id in self.messagesDict:
                     msg = self.messagesDict[newMsg.id]
                 else:
                     msg = self.addMessage(newMsg)
@@ -224,7 +224,7 @@ class PoFile:
             notNewMessages = [m for m in self.messages if m.id not in newIds]
             del self.messages[:]
             for newMsg in newMessages:
-                if self.messagesDict.has_key(newMsg.id):
+                if newMsg.id in self.messagesDict:
                     msg = self.messagesDict[newMsg.id]
                     self.messages.append(msg)
                 else:
@@ -240,7 +240,7 @@ class PoFile:
             fb = ''
             if not self.isPot:
                 # I must add fallbacks
-                if fallbacks.has_key(self.language):
+                if self.language in fallbacks:
                     fb = '"X-is-fallback-for: %s\\n"' % fallbacks[self.language]
             f.write(poHeader % (self.applicationName, creationTime,
                                 self.language, self.language, self.domain, fb))
diff --git a/gen/utils.py b/gen/utils.py
index fdaf8a1..ac18be5 100644
--- a/gen/utils.py
+++ b/gen/utils.py
@@ -1,7 +1,8 @@
 # ------------------------------------------------------------------------------
-import re, os, os.path, base64, urllib
+import re, os, os.path, base64, urllib.request, urllib.parse, urllib.error
 from appy.px import Px
 from appy.shared import utils as sutils
+import collections
 
 # Function for creating a Zope object ------------------------------------------
 def createObject(folder, id, className, appName, wf=True, noSecurity=False):
@@ -10,8 +11,8 @@ def createObject(folder, id, className, appName, wf=True, noSecurity=False):
        creation of the config object), computing workflow-related info is not
        possible at this time. This is why this function can be called with
        p_wf=False.'''
-    exec 'from Products.%s.%s import %s as ZopeClass' % \
-         (appName, className, className)
+    exec('from Products.%s.%s import %s as ZopeClass' % \
+         (appName, className, className))
     # Get the tool. It may not be present yet, maybe are we creating it now.
     if folder.meta_type.endswith('Folder'):
         # p_folder is a standard Zope (temp) folder.
@@ -178,7 +179,7 @@ def callMethod(obj, method, klass=None, cache=True):
     if methodType == 'staticmethod':
         method = method.__get__(klass)
     elif methodType == 'instancemethod':
-        method = method.im_func
+        method = method.__func__
     # Call the method if cache is not needed
     if not cache: return method(obj)
     # If first arg of method is named "tool" instead of the traditional "self",
@@ -187,7 +188,7 @@ def callMethod(obj, method, klass=None, cache=True):
     # Every method call, even on different instances, will be cached in a unique
     # key.
     cheat = False
-    if not klass and (method.func_code.co_varnames[0] == 'tool'):
+    if not klass and (method.__code__.co_varnames[0] == 'tool'):
         prefix = obj.klass.__name__
         obj = obj.tool
         cheat = True
@@ -200,7 +201,7 @@ def callMethod(obj, method, klass=None, cache=True):
         else:
             prefix = obj.uid
     # Second part of the key: p_method name
-    key = '%s:%s' % (prefix, method.func_name)
+    key = '%s:%s' % (prefix, method.__name__)
     # Return the cached value if present in the method cache.
     if key in rq.methodCache:
         return rq.methodCache[key]
@@ -216,20 +217,20 @@ def readCookie(request):
        (None, None).'''
     cookie = request.get('_appy_', None)
     if not cookie: return None, None
-    cookieValue = base64.decodestring(urllib.unquote(cookie))
+    cookieValue = base64.decodestring(urllib.parse.unquote(cookie))
     if ':' in cookieValue: return cookieValue.split(':')
     return None, None
 
 def writeCookie(login, password, request):
     '''Encode p_login and p_password into the cookie set in the p_request.'''
     cookieValue = base64.encodestring('%s:%s' % (login, password)).rstrip()
-    cookieValue = urllib.quote(cookieValue)
+    cookieValue = urllib.parse.quote(cookieValue)
     request.RESPONSE.setCookie('_appy_', cookieValue, path='/')
 
 # ------------------------------------------------------------------------------
 def initMasterValue(v):
     '''Standardizes p_v as a list of strings, excepted if p_v is a method.'''
-    if callable(v): return v
+    if isinstance(v, collections.Callable): return v
     if not isinstance(v, bool) and not v: res = []
     elif type(v) not in sutils.sequenceTypes: res = [v]
     else: res = v
@@ -243,7 +244,7 @@ class No:
        instead. When creating such an instance, you can specify an error
        message.'''
     def __init__(self, msg): self.msg = msg
-    def __nonzero__(self): return False
+    def __bool__(self): return False
     def __repr__(self): return '<No: %s>' % self.msg
 
 # ------------------------------------------------------------------------------
diff --git a/gen/wrappers/ToolWrapper.py b/gen/wrappers/ToolWrapper.py
index 87d7646..e3e00c6 100644
--- a/gen/wrappers/ToolWrapper.py
+++ b/gen/wrappers/ToolWrapper.py
@@ -424,7 +424,7 @@ class ToolWrapper(AbstractWrapper):
               '<tr><th></th><th>%s</th></tr>' % \
               self.translate('last_user_access')
         rows = []
-        for userId, lastAccess in self.o.loggedUsers.items():
+        for userId, lastAccess in list(self.o.loggedUsers.items()):
             user = self.search1('User', noSecurity=True, login=userId)
             if not user: continue # Could have been deleted in the meanwhile
             fmt = '%s (%s)' % (self.dateFormat, self.hourFormat)
@@ -515,7 +515,7 @@ class ToolWrapper(AbstractWrapper):
                 failed += subFailed
             try:
                 startObject.reindex()
-            except Exception, e:
+            except Exception as e:
                 failed.append(startObject)
             return nb, failed
 
diff --git a/gen/wrappers/UserWrapper.py b/gen/wrappers/UserWrapper.py
index 3844d1d..df6619f 100644
--- a/gen/wrappers/UserWrapper.py
+++ b/gen/wrappers/UserWrapper.py
@@ -343,7 +343,7 @@ class UserWrapper(AbstractWrapper):
         if not localRoles: return res
         # Gets the logins of this user and all its groups.
         logins = self.getLogins()
-        for login, roles in localRoles.iteritems():
+        for login, roles in localRoles.items():
             # Ignore logins not corresponding to this user.
             if login not in logins: continue
             for role in roles:
@@ -388,7 +388,7 @@ class UserWrapper(AbstractWrapper):
         if not localRoles: return
         # Gets the logins of this user and all its groups.
         userLogins = self.getLogins()
-        for login, roles in localRoles.iteritems():
+        for login, roles in localRoles.items():
             # Ignore logins not corresponding to this user.
             if login not in userLogins: continue
             for role in roles:
diff --git a/gen/wrappers/__init__.py b/gen/wrappers/__init__.py
index 79dec60..a2858fc 100644
--- a/gen/wrappers/__init__.py
+++ b/gen/wrappers/__init__.py
@@ -861,7 +861,7 @@ class AbstractWrapper(object):
         if len(self.__class__.__bases__) > 1:
             # There is a custom user class
             custom = self.__class__.__bases__[-1]
-            if custom.__dict__.has_key(methodName):
+            if methodName in custom.__dict__:
                 return custom.__dict__[methodName]
 
     def _callCustom(self, methodName, *args, **kwargs):
@@ -973,7 +973,7 @@ class AbstractWrapper(object):
            present, will not be called; any other defined method will not be
            called neither (ie, Ref.insert, Ref.beforeLink, Ref.afterLink...).
         '''
-        isField = isinstance(fieldNameOrClass, basestring)
+        isField = isinstance(fieldNameOrClass, str)
         tool = self.tool.o
         # Determine the class of the object to create
         if isField:
@@ -984,7 +984,7 @@ class AbstractWrapper(object):
             klass = fieldNameOrClass
             portalType = tool.getPortalType(klass)
         # Determine object id
-        if kwargs.has_key('id'):
+        if 'id' in kwargs:
             objId = kwargs['id']
             del kwargs['id']
         else:
@@ -1002,7 +1002,7 @@ class AbstractWrapper(object):
                                noSecurity=noSecurity)
         appyObj = zopeObj.appy()
         # Set object attributes
-        for attrName, attrValue in kwargs.iteritems():
+        for attrName, attrValue in kwargs.items():
             try:
                 setattr(appyObj, attrName, attrValue)
             except AttributeError, ae:
@@ -1183,8 +1183,8 @@ class AbstractWrapper(object):
             # Get the Appy object from the brain
             if noSecurity: method = '_unrestrictedGetObject'
             else: method = 'getObject'
-            exec 'obj = brain.%s().appy()' % method
-            exec expression
+            exec('obj = brain.%s().appy()' % method)
+            exec(expression)
         return ctx
 
     def reindex(self, fields=None, unindex=False):
@@ -1249,7 +1249,7 @@ class AbstractWrapper(object):
             else:
                 return xml
         elif format == 'csv':
-            if isinstance(at, basestring):
+            if isinstance(at, str):
                 marshaller = CsvMarshaller(include=include, exclude=exclude)
                 return marshaller.marshall(self)
             else:
diff --git a/pod/actions.py b/pod/actions.py
index 1e78d3b..095de5f 100644
--- a/pod/actions.py
+++ b/pod/actions.py
@@ -101,7 +101,7 @@ class BufferAction:
         try:
             res = self._evalExpr(expr, context)
             error = False
-        except Exception, e:
+        except Exception as e:
             res = None
             errorMessage = EVAL_ERROR % (expr, self.getExceptionLine(e))
             self.manageError(result, context, errorMessage)
@@ -134,7 +134,7 @@ class BufferAction:
             error = False
             try:
                 feRes = eval(self.fromExpr, context)
-            except Exception, e:
+            except Exception as e:
                 msg = FROM_EVAL_ERROR% (self.fromExpr, self.getExceptionLine(e))
                 self.manageError(result, context, msg)
                 error = True
@@ -240,7 +240,7 @@ class ForAction(BufferAction):
             return
         # Remember variable hidden by iter if any
         hasHiddenVariable = False
-        if context.has_key(self.iter):
+        if self.iter in context:
             hiddenVariable = context[self.iter]
             hasHiddenVariable = True
         # In the case of cells, initialize some values
diff --git a/pod/buffers.py b/pod/buffers.py
index 01397f1..3bff041 100644
--- a/pod/buffers.py
+++ b/pod/buffers.py
@@ -80,15 +80,15 @@ NULL_ACTION_ERROR = 'There was a problem with this action. Possible causes: ' \
 class BufferIterator:
     def __init__(self, buffer):
         self.buffer = buffer
-        self.remainingSubBufferIndexes = self.buffer.subBuffers.keys()
-        self.remainingElemIndexes = self.buffer.elements.keys()
+        self.remainingSubBufferIndexes = list(self.buffer.subBuffers.keys())
+        self.remainingElemIndexes = list(self.buffer.elements.keys())
         self.remainingSubBufferIndexes.sort()
         self.remainingElemIndexes.sort()
 
     def hasNext(self):
         return self.remainingSubBufferIndexes or self.remainingElemIndexes
 
-    def next(self):
+    def __next__(self):
         nextSubBufferIndex = None
         if self.remainingSubBufferIndexes:
             nextSubBufferIndex = self.remainingSubBufferIndexes[0]
@@ -131,7 +131,7 @@ class Buffer:
         return subBuffer
 
     def removeLastSubBuffer(self):
-        subBufferIndexes = self.subBuffers.keys()
+        subBufferIndexes = list(self.subBuffers.keys())
         subBufferIndexes.sort()
         lastIndex = subBufferIndexes.pop()
         del self.subBuffers[lastIndex]
@@ -176,7 +176,7 @@ class Buffer:
         self.write('<%s' % elem)
         # Some table elements must be patched (pod only)
         if self.pod: self.patchTableElement(elem, attrs)
-        for name, value in attrs.items():
+        for name, value in list(attrs.items()):
             if ignoreAttrs and (name in ignoreAttrs): continue
             if renamedAttrs and (name in renamedAttrs): name=renamedAttrs[name]
             # If the value begins with ':', it is a Python expression. Else,
@@ -244,7 +244,7 @@ class FileBuffer(Buffer):
             res, escape = expr.evaluate(self.env.context)
             if escape: self.dumpContent(res)
             else: self.write(res)
-        except Exception, e:
+        except Exception as e:
             if not self.env.raiseOnError:
                 PodError.dump(self, EVAL_EXPR_ERROR % (expression, e),
                               dumpTb=False)
@@ -271,7 +271,7 @@ class MemoryBuffer(Buffer):
 
     def __init__(self, env, parent):
         Buffer.__init__(self, env, parent)
-        self.content = u''
+        self.content = ''
         self.elements = {}
         self.action = None
 
@@ -297,7 +297,7 @@ class MemoryBuffer(Buffer):
 
     def getIndex(self, podElemName):
         res = -1
-        for index, podElem in self.elements.iteritems():
+        for index, podElem in self.elements.items():
             if podElem.__class__.__name__.lower() == podElemName:
                 if index > res:
                     res = index
@@ -305,7 +305,7 @@ class MemoryBuffer(Buffer):
 
     def getMainElement(self):
         res = None
-        if self.elements.has_key(0):
+        if 0 in self.elements:
             res = self.elements[0]
         return res
 
@@ -317,7 +317,7 @@ class MemoryBuffer(Buffer):
         if elem != mainElem: return
         # elem is the same as the main elem. But is it really the main elem, or
         # the same elem, found deeper in the buffer?
-        for index, iElem in self.elements.iteritems():
+        for index, iElem in self.elements.items():
             foundElem = None
             if hasattr(iElem, 'OD'):
                 if iElem.OD:
@@ -331,7 +331,7 @@ class MemoryBuffer(Buffer):
     def unreferenceElement(self, elem):
         # Find last occurrence of this element
         elemIndex = -1
-        for index, iElem in self.elements.iteritems():
+        for index, iElem in self.elements.items():
             foundElem = None
             if hasattr(iElem, 'OD'):
                 # A POD element
@@ -347,7 +347,7 @@ class MemoryBuffer(Buffer):
     def pushSubBuffer(self, subBuffer):
         '''Sets p_subBuffer at the very end of the buffer.'''
         subIndex = None
-        for index, aSubBuffer in self.subBuffers.iteritems():
+        for index, aSubBuffer in self.subBuffers.items():
             if aSubBuffer == subBuffer:
                 subIndex = index
                 break
@@ -356,7 +356,7 @@ class MemoryBuffer(Buffer):
             # in the parent (if it is a temp buffer generated from a cut)
             del self.subBuffers[subIndex]
             self.subBuffers[self.getLength()] = subBuffer
-            self.content += u' '
+            self.content += ' '
 
     def transferAllContent(self):
         '''Transfer all content to parent.'''
@@ -370,10 +370,10 @@ class MemoryBuffer(Buffer):
             oldParentLength = self.parent.getLength()
             self.parent.write(self.content)
             # Transfer elements
-            for index, podElem in self.elements.iteritems():
+            for index, podElem in self.elements.items():
                 self.parent.elements[oldParentLength + index] = podElem
             # Transfer sub-buffers
-            for index, buf in self.subBuffers.iteritems():
+            for index, buf in self.subBuffers.items():
                 self.parent.subBuffers[oldParentLength + index] = buf
         # Empty the buffer
         MemoryBuffer.__init__(self, self.env, self.parent)
@@ -391,7 +391,7 @@ class MemoryBuffer(Buffer):
                 elem.colIndex = elem.tableInfo.curColIndex
         if elem == 'x':
             # See comment on similar statement in the method below.
-            self.content += u' '
+            self.content += ' '
 
     def addExpression(self, expression, tiedHook=None):
         # Create the POD expression
@@ -400,20 +400,20 @@ class MemoryBuffer(Buffer):
         self.elements[self.getLength()] = expr
         # To be sure that an expr and an elem can't be found at the same index
         # in the buffer.
-        self.content += u' '
+        self.content += ' '
 
     def addAttributes(self):
         '''pod-only: adds an Attributes instance into this buffer.'''
         attrs = Attributes(self.env)
         self.elements[self.getLength()] = attrs
-        self.content += u' '
+        self.content += ' '
         return attrs
 
     def addAttribute(self, name, expr):
         '''px-only: adds an Attribute instance into this buffer.'''
         attr = Attribute(name, expr)
         self.elements[self.getLength()] = attr
-        self.content += u' '
+        self.content += ' '
         return attr
 
     def _getVariables(self, expr):
@@ -453,7 +453,7 @@ class MemoryBuffer(Buffer):
                 raise ParsingError(
                     ELEMENT_NOT_FOUND % (podElem, str([
                         e.__class__.__name__.lower() \
-                        for e in self.elements.values()])))
+                        for e in list(self.elements.values())])))
             podElem = self.elements[indexPodElem]
             # Check the 'from' clause
             fromClause = None
@@ -471,7 +471,7 @@ class MemoryBuffer(Buffer):
                 self.env.ifActions.append(self.action)
                 if self.action.name:
                     # We must register this action as a named action
-                    if self.env.namedIfActions.has_key(self.action.name):
+                    if self.action.name in self.env.namedIfActions:
                         raise ParsingError(DUPLICATE_NAMED_IF)
                     self.env.namedIfActions[self.action.name] = self.action
             elif actionType == 'else':
@@ -480,7 +480,7 @@ class MemoryBuffer(Buffer):
                 # Does the "else" action reference a named "if" action?
                 ifReference = subExpr.strip()
                 if ifReference:
-                    if not self.env.namedIfActions.has_key(ifReference):
+                    if ifReference not in self.env.namedIfActions:
                         raise ParsingError(ELSE_WITHOUT_NAMED_IF % ifReference)
                     linkedIfAction = self.env.namedIfActions[ifReference]
                     # This "else" action "consumes" the "if" action: this way,
@@ -510,7 +510,7 @@ class MemoryBuffer(Buffer):
                 self.action = NullAction(statementName, self, None, podElem,
                                          None, source, fromClause)
             res = indexPodElem
-        except ParsingError, ppe:
+        except ParsingError as ppe:
             PodError.dump(self, ppe, removeFirstLine=True)
         return res
 
@@ -552,7 +552,7 @@ class MemoryBuffer(Buffer):
         elementsToDelete = []
         mustShift = False
         while iter.hasNext():
-            itemIndex, item = iter.next()
+            itemIndex, item = next(iter)
             if keepFirstPart:
                 if itemIndex >= index:
                     newIndex = itemIndex-index
@@ -580,11 +580,11 @@ class MemoryBuffer(Buffer):
                 del self.subBuffers[subIndex]
         if mustShift:
             elements = {}
-            for elemIndex, elem in self.elements.iteritems():
+            for elemIndex, elem in self.elements.items():
                 elements[elemIndex-index] = elem
             self.elements = elements
             subBuffers = {}
-            for subIndex, buf in self.subBuffers.iteritems():
+            for subIndex, buf in self.subBuffers.items():
                 subBuffers[subIndex-index] = buf
             self.subBuffers = subBuffers
         # Manage content
@@ -598,7 +598,7 @@ class MemoryBuffer(Buffer):
 
     def getElementIndexes(self, expressions=True):
         res = []
-        for index, elem in self.elements.iteritems():
+        for index, elem in self.elements.items():
             condition = isinstance(elem, Expression) or \
                         isinstance(elem, Attributes)
             if not expressions:
@@ -696,7 +696,7 @@ class MemoryBuffer(Buffer):
             iter = BufferIterator(self)
             currentIndex = self.getStartIndex(removeMainElems)
             while iter.hasNext():
-                index, evalEntry = iter.next()
+                index, evalEntry = next(iter)
                 result.write(self.content[currentIndex:index])
                 currentIndex = index + 1
                 if isinstance(evalEntry, Expression):
@@ -708,7 +708,7 @@ class MemoryBuffer(Buffer):
                         # This exception has already been treated (see the 
                         # "except" block below). Simply re-raise it when needed.
                         if self.env.raiseOnError: raise e
-                    except Exception, e:
+                    except Exception as e:
                         if not self.env.raiseOnError:
                             PodError.dump(result, EVAL_EXPR_ERROR % (
                                           evalEntry.expr, e))
@@ -729,5 +729,5 @@ class MemoryBuffer(Buffer):
 
     def clean(self):
         '''Cleans the buffer content.'''
-        self.content = u''
+        self.content = ''
 # ------------------------------------------------------------------------------
diff --git a/pod/converter.py b/pod/converter.py
index c00592e..f3cf8c9 100644
--- a/pod/converter.py
+++ b/pod/converter.py
@@ -109,7 +109,7 @@ class Converter:
                 res = res[self.inputType]
         else:
             raise ConverterError(BAD_RESULT_TYPE % (self.resultType,
-                                                    FILE_TYPES.keys()))
+                                                    list(FILE_TYPES.keys())))
         return res
 
     def getResultUrl(self):
@@ -275,7 +275,7 @@ class ConverterScript:
             '         %s.\n' \
             ' "python" should be a UNO-enabled Python interpreter (ie the ' \
             '  one which is included in the LibreOffice distribution).' % \
-            str(FILE_TYPES.keys())
+            str(list(FILE_TYPES.keys()))
     def run(self):
         optParser = OptionParser(usage=ConverterScript.usage)
         optParser.add_option("-p", "--port", dest="port",
diff --git a/pod/doc_importers.py b/pod/doc_importers.py
index 41be73f..4f1f366 100644
--- a/pod/doc_importers.py
+++ b/pod/doc_importers.py
@@ -17,7 +17,7 @@
 # Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,USA.
 
 # ------------------------------------------------------------------------------
-import os, os.path, time, shutil, struct, random, urlparse
+import os, os.path, time, shutil, struct, random, urllib.parse
 from appy.pod import PodError
 from appy.pod.odf_parser import OdfEnvironment
 from appy.shared import mimeTypesExts
@@ -53,7 +53,7 @@ class DocImporter:
         if at and not at.startswith('http') and not os.path.isfile(at):
             raise PodError(FILE_NOT_FOUND % at)
         self.format = format
-        self.res = u''
+        self.res = ''
         self.renderer = renderer
         self.ns = renderer.currentParser.env.namespaces
         # Unpack some useful namespaces
@@ -285,7 +285,7 @@ class ImageImporter(DocImporter):
     def moveFile(self, at, importPath):
         '''Copies file at p_at into the ODT file at p_importPath.'''
         # Has this image already been imported ?
-        for imagePath, imageAt in self.fileNames.iteritems():
+        for imagePath, imageAt in self.fileNames.items():
             if imageAt == at:
                 # Yes!
                 i = importPath.rfind(self.pictFolder) + 1
@@ -327,7 +327,7 @@ class ImageImporter(DocImporter):
             # The imageResolver is a Zope application. From it, we will
             # retrieve the object on which the image is stored and get
             # the file to download.
-            urlParts = urlparse.urlsplit(at)
+            urlParts = urllib.parse.urlsplit(at)
             path = urlParts[2][1:].split('/')[:-1]
             try:
                 obj = imageResolver.unrestrictedTraverse(path)
diff --git a/pod/elements.py b/pod/elements.py
index f7679ab..c4daf7b 100644
--- a/pod/elements.py
+++ b/pod/elements.py
@@ -148,7 +148,7 @@ class Expression(PodElement):
         # pod/px result.
         resultType = res.__class__.__name__
         if resultType == 'NoneType':
-            res = u''
+            res = ''
         elif resultType == 'str':
             res = res.decode('utf-8')
         elif resultType == 'unicode':
@@ -160,7 +160,7 @@ class Expression(PodElement):
             # Force escapeXml to False.
             escapeXml = False
         else:
-            res = unicode(res)
+            res = str(res)
         return res, escapeXml
 
 class Attributes(PodElement):
@@ -199,7 +199,7 @@ class Attributes(PodElement):
         try:
             self.tiedExpression.evaluate(context)
             self.tiedExpression.evaluated = True
-        except Exception, e:
+        except Exception as e:
             # Don't set "evaluated" to True. This way, when the buffer will
             # evaluate the expression directly, we will really evaluate it, so
             # the error will be dumped into the pod result.
@@ -208,7 +208,7 @@ class Attributes(PodElement):
         self.computeAttributes(self.tiedExpression)
         # Now, self.attrs has been populated. Transform it into a string.
         res = ''
-        for name, value in self.attrs.iteritems():
+        for name, value in self.attrs.items():
             res += ' %s=%s' % (name, quoteattr(value))
         return res
 
diff --git a/pod/pod_parser.py b/pod/pod_parser.py
index dafd5b6..720474f 100644
--- a/pod/pod_parser.py
+++ b/pod/pod_parser.py
@@ -50,7 +50,7 @@ class OdInsert:
     def resolve(self, namespaces):
         '''Replaces all unresolved namespaces in p_odtChunk, thanks to the dict
            of p_namespaces.'''
-        for nsName, nsUri in self.nsUris.iteritems():
+        for nsName, nsUri in self.nsUris.items():
             self.odtChunk = re.sub('@%s@' % nsName, namespaces[nsUri],
                                    self.odtChunk)
         return self.odtChunk
@@ -126,14 +126,14 @@ class PodEnvironment(OdfEnvironment):
         res = {}
         for insert in self.inserts:
             elemName = insert.elem.getFullName(self.namespaces)
-            if not res.has_key(elemName):
+            if elemName not in res:
                 res[elemName] = insert
         return res
 
     def manageInserts(self):
         '''We just dumped the start of an elem. Here we will insert any odt
            chunk if needed.'''
-        if self.inserts.has_key(self.currentElem.elem):
+        if self.currentElem.elem in self.inserts:
             insert = self.inserts[self.currentElem.elem]
             self.currentBuffer.write(insert.resolve(self.namespaces))
             # The insert is destroyed after single use
@@ -160,12 +160,12 @@ class PodEnvironment(OdfEnvironment):
         elif elem == Cell.OD.elem:
             colspan = 1
             attrSpan = self.tags['number-columns-spanned']
-            if self.currentElem.attrs.has_key(attrSpan):
+            if attrSpan in self.currentElem.attrs:
                 colspan = int(self.currentElem.attrs[attrSpan])
             self.getTable().curColIndex += colspan
         elif elem == self.tags['table-column']:
             attrs = self.currentElem.attrs
-            if attrs.has_key(self.tags['number-columns-repeated']):
+            if self.tags['number-columns-repeated'] in attrs:
                 self.getTable().nbOfColumns += int(
                     attrs[self.tags['number-columns-repeated']])
             else:
@@ -254,8 +254,8 @@ class PodParser(OdfParser):
             e.state = e.READING_EXPRESSION
             e.exprHasStyle = False
         elif (elem == e.tags['table-cell']) and \
-             attrs.has_key(e.tags['formula']) and \
-             attrs.has_key(e.tags['value-type']) and \
+             e.tags['formula'] in attrs and \
+             e.tags['value-type'] in attrs and \
              (attrs[e.tags['value-type']] == 'string') and \
              attrs[e.tags['formula']].startswith('of:="'):
             # In an ODS template, any cell containing a formula of type "string"
diff --git a/pod/renderer.py b/pod/renderer.py
index 32a1df9..354b77d 100644
--- a/pod/renderer.py
+++ b/pod/renderer.py
@@ -18,7 +18,11 @@
 
 # ------------------------------------------------------------------------------
 import zipfile, shutil, xml.sax, os, os.path, re, mimetypes, time
-from UserDict import UserDict
+#python3 compat
+try:
+    from UserDict import UserDict
+except ImportError:
+    from collections import UserDict
 import appy.pod
 from appy.pod import PodError
 from appy.shared import mimeTypes, mimeTypesExts
@@ -80,7 +84,7 @@ CONTENT_POD_FONTS = '<@style@:font-face @style@:name="PodStarSymbol" ' \
                     '@svg@:font-family="StarSymbol"/>'
 
 # Default text styles added by pod in styles.xml
-f = file('%s/styles.in.styles.xml' % os.path.dirname(appy.pod.__file__))
+f = open('%s/styles.in.styles.xml' % os.path.dirname(appy.pod.__file__))
 STYLES_POD_STYLES = f.read()
 f.close()
 
@@ -263,7 +267,7 @@ class Renderer:
 
     imageFormats = ('png', 'jpeg', 'jpg', 'gif', 'svg')
     ooFormats = ('odt',)
-    convertibleFormats = FILE_TYPES.keys()
+    convertibleFormats = list(FILE_TYPES.keys())
     def importDocument(self, content=None, at=None, format=None,
                        anchor='as-char', wrapInPara=True, size=None,
                        sizeUnit='cm', style=None,
@@ -309,7 +313,7 @@ class Renderer:
             format = os.path.splitext(at)[1][1:]
         else:
             # If format is a mimeType, convert it to an extension
-            if mimeTypesExts.has_key(format):
+            if format in mimeTypesExts:
                 format = mimeTypesExts[format]
         isImage = False
         isOdt = False
@@ -370,9 +374,9 @@ class Renderer:
             f = open(self.result, 'w')
             f.write('Hello')
             f.close()
-        except OSError, oe:
+        except OSError as oe:
             raise PodError(CANT_WRITE_RESULT % (self.result, oe))
-        except IOError, ie:
+        except IOError as ie:
             raise PodError(CANT_WRITE_RESULT % (self.result, ie))
         self.result = os.path.abspath(self.result)
         os.remove(self.result)
@@ -381,7 +385,7 @@ class Renderer:
         self.tempFolder = '%s.%f' % (absResult, time.time())
         try:
             os.mkdir(self.tempFolder)
-        except OSError, oe:
+        except OSError as oe:
             raise PodError(CANT_WRITE_TEMP_FOLDER % (self.result, oe))
 
     def patchManifest(self):
@@ -390,7 +394,7 @@ class Renderer:
         if self.fileNames:
             j = os.path.join
             toInsert = ''
-            for fileName in self.fileNames.iterkeys():
+            for fileName in self.fileNames.keys():
                 if fileName.endswith('.svg'):
                     fileName = os.path.splitext(fileName)[0] + '.png'
                 mimeType = mimetypes.guess_type(fileName)[0]
@@ -442,7 +446,7 @@ class Renderer:
             if 'span[font-style=italic]' not in stylesMapping:
                 stylesMapping['span[font-style=italic]'] = 'podItalic'
             self.stylesManager.stylesMapping = stylesMapping
-        except PodError, po:
+        except PodError as po:
             self.contentParser.env.currentBuffer.content.close()
             self.stylesParser.env.currentBuffer.content.close()
             if os.path.exists(self.tempFolder):
@@ -454,14 +458,14 @@ class Renderer:
         loOutput = ''
         try:
             if (not isinstance(self.ooPort, int)) and \
-               (not isinstance(self.ooPort, long)):
+               (not isinstance(self.ooPort, int)):
                 raise PodError(BAD_OO_PORT % str(self.ooPort))
             try:
                 from appy.pod.converter import Converter, ConverterError
                 try:
                     Converter(resultName, resultType, self.ooPort,
                               self.stylesTemplate).run()
-                except ConverterError, ce:
+                except ConverterError as ce:
                     raise PodError(CONVERT_ERROR % str(ce))
             except ImportError:
                 # I do not have UNO. So try to launch a UNO-enabled Python
@@ -485,13 +489,13 @@ class Renderer:
                     self.ooPort)
                 if self.stylesTemplate: cmd += ' -t%s' % self.stylesTemplate
                 loOutput = executeCommand(cmd)
-        except PodError, pe:
+        except PodError as pe:
             # When trying to call LO in server mode for producing ODT or ODS
             # (=forceOoCall=True), if an error occurs we have nevertheless
             # an ODT or ODS to return to the user. So we produce a warning
             # instead of raising an error.
             if (resultType in self.templateTypes) and self.forceOoCall:
-                print(WARNING_INCOMPLETE_OD % str(pe))
+                print((WARNING_INCOMPLETE_OD % str(pe)))
             else:
                 raise pe
         return loOutput
@@ -501,7 +505,7 @@ class Renderer:
            (ods or odt). If self.template is a string, it is a file name and we
            simply get its extension. Else, it is a binary file in a StringIO
            instance, and we seek the mime type from the first bytes.'''
-        if isinstance(self.template, basestring):
+        if isinstance(self.template, str):
             res = os.path.splitext(self.template)[1][1:]
         else:
             # A StringIO instance
@@ -534,8 +538,8 @@ class Renderer:
         if self.finalizeFunction:
             try:
                 self.finalizeFunction(self.unzipFolder)
-            except Exception, e:
-                print(WARNING_FINALIZE_ERROR % str(e))
+            except Exception as e:
+                print((WARNING_FINALIZE_ERROR % str(e)))
         # Re-zip the result, first as an OpenDocument file of the same type as
         # the POD template (odt, ods...)
         resultExt = self.getTemplateType()
diff --git a/pod/styles_manager.py b/pod/styles_manager.py
index 50f67f3..bfe026e 100644
--- a/pod/styles_manager.py
+++ b/pod/styles_manager.py
@@ -18,7 +18,12 @@
 
 # ------------------------------------------------------------------------------
 import re, os.path
-from UserDict import UserDict
+#python3 compat
+try:
+    from UserDict import UserDict
+except ImportError:
+    from collections import UserDict
+    
 import appy.pod
 from appy.pod import *
 from appy.pod.odf_parser import OdfEnvironment, OdfParser
@@ -93,7 +98,7 @@ class Styles(UserDict):
         '''Tries to find a style which has level p_level. Returns None if no
            such style exists.'''
         res = None
-        for style in self.itervalues():
+        for style in self.values():
             if (style.family == 'paragraph') and (style.outlineLevel == level):
                 res = style
                 break
@@ -102,7 +107,7 @@ class Styles(UserDict):
         '''Gets the style that has this p_displayName. Returns None if not
            found.'''
         res = None
-        for style in self.itervalues():
+        for style in self.values():
             if style.displayName == displayName:
                 res = style
                 break
@@ -111,9 +116,9 @@ class Styles(UserDict):
         '''Returns a list of all the styles of the given p_stylesType.'''
         res = []
         if stylesType == 'all':
-            res = self.values()
+            res = list(self.values())
         else:
-            for style in self.itervalues():
+            for style in self.values():
                 if (style.family == stylesType) and style.displayName:
                     res.append(style)
         return res
@@ -145,22 +150,22 @@ class StylesParser(OdfParser):
             displayNameAttr = '%s:display-name' % e.ns(e.NS_STYLE)
             # Create the style
             style = Style(name=attrs[nameAttr], family=attrs[familyAttr])
-            if attrs.has_key(classAttr):
+            if classAttr in attrs:
                 style.styleClass = attrs[classAttr]
-            if attrs.has_key(displayNameAttr):
+            if displayNameAttr in attrs:
                 style.displayName = attrs[displayNameAttr]
             # Record this style in the environment
             e.styles[style.name] = style
             e.currentStyle = style
             levelKey = '%s:default-outline-level' % e.ns(e.NS_STYLE)
-            if attrs.has_key(levelKey) and attrs[levelKey].strip():
+            if levelKey in attrs and attrs[levelKey].strip():
                 style.outlineLevel = int(attrs[levelKey])
         else:
             if e.state == PARSING_STYLE:
                 # I am parsing tags within the style.
                 if elem == ('%s:text-properties' % e.ns(e.NS_STYLE)):
                     fontSizeKey = '%s:font-size' % e.ns(e.NS_FO)
-                    if attrs.has_key(fontSizeKey):
+                    if fontSizeKey in attrs:
                         e.currentStyle.setFontSize(attrs[fontSizeKey])
     def endElement(self, elem):
         e = OdfParser.endElement(self, elem)
@@ -250,14 +255,14 @@ class StylesManager:
         if not isinstance(stylesMapping, dict) and \
            not isinstance(stylesMapping, UserDict):
             raise PodError(MAPPING_NOT_DICT)
-        for xhtmlStyleName, odtStyleName in stylesMapping.iteritems():
-            if not isinstance(xhtmlStyleName, basestring):
+        for xhtmlStyleName, odtStyleName in stylesMapping.items():
+            if not isinstance(xhtmlStyleName, str):
                 raise PodError(MAPPING_ELEM_NOT_STRING)
             if (xhtmlStyleName == 'h*') and \
                 not isinstance(odtStyleName, int):
                 raise PodError(MAPPING_OUTLINE_DELTA_NOT_INT)
             if (xhtmlStyleName != 'h*') and \
-                not isinstance(odtStyleName, basestring):
+                not isinstance(odtStyleName, str):
                 raise PodError(MAPPING_ELEM_NOT_STRING)
             if (xhtmlStyleName != 'h*') and \
                ((not xhtmlStyleName) or (not odtStyleName)):
@@ -278,7 +283,7 @@ class StylesManager:
             if xhtmlStyleName != 'h*':
                 odtStyle = self.styles.getStyle(odtStyleName)
                 if not odtStyle:
-                    if self.podSpecificStyles.has_key(odtStyleName):
+                    if odtStyleName in self.podSpecificStyles:
                         odtStyle = self.podSpecificStyles[odtStyleName]
                     else:
                         raise PodError(STYLE_NOT_FOUND % odtStyleName)
@@ -311,7 +316,7 @@ class StylesManager:
            This method returns True if p_attrs contains the winning (name,value)
            pairs that match those in p_matchingAttrs. Note that ALL attrs in
            p_matchingAttrs must be present in p_attrs.'''
-        for name, value in matchingAttrs.iteritems():
+        for name, value in matchingAttrs.items():
             if name not in attrs: return
             if value != attrs[name]: return
         return True
@@ -356,29 +361,29 @@ class StylesManager:
         '''
         res = None
         cssStyleName = None
-        if attrs and attrs.has_key('class'):
+        if attrs and 'class' in attrs:
             cssStyleName = attrs['class']
         if classValue:
             cssStyleName = classValue
         # (1)
-        if localStylesMapping.has_key(cssStyleName):
+        if cssStyleName in localStylesMapping:
             res = localStylesMapping[cssStyleName]
         # (2)
-        if (not res) and localStylesMapping.has_key(elem):
+        if (not res) and elem in localStylesMapping:
             styles = localStylesMapping[elem]
             res = self.getStyleFromMapping(elem, attrs, styles)
         # (3)
-        if (not res) and self.stylesMapping.has_key(cssStyleName):
+        if (not res) and cssStyleName in self.stylesMapping:
             res = self.stylesMapping[cssStyleName]
         # (4)
-        if (not res) and self.stylesMapping.has_key(elem):
+        if (not res) and elem in self.stylesMapping:
             styles = self.stylesMapping[elem]
             res = self.getStyleFromMapping(elem, attrs, styles)
         # (5)
-        if (not res) and self.styles.has_key(cssStyleName):
+        if (not res) and cssStyleName in self.styles:
             res = self.styles[cssStyleName]
         # (6)
-        if (not res) and self.podSpecificStyles.has_key(cssStyleName):
+        if (not res) and cssStyleName in self.podSpecificStyles:
             res = self.podSpecificStyles[cssStyleName]
         # (7)
         if not res:
@@ -386,9 +391,9 @@ class StylesManager:
             if elem in XHTML_HEADINGS:
                 # Is there a delta that must be taken into account ?
                 outlineDelta = 0
-                if localStylesMapping.has_key('h*'):
+                if 'h*' in localStylesMapping:
                     outlineDelta += localStylesMapping['h*']
-                elif self.stylesMapping.has_key('h*'):
+                elif 'h*' in self.stylesMapping:
                     outlineDelta += self.stylesMapping['h*']
                 outlineLevel = int(elem[1]) + outlineDelta
                 # Normalize the outline level
diff --git a/pod/test/Tester.py b/pod/test/Tester.py
index b2ca636..9e0748d 100644
--- a/pod/test/Tester.py
+++ b/pod/test/Tester.py
@@ -38,7 +38,7 @@ class AnnotationsRemover(OdfParser):
        machine-specific info, like absolute paths to the python files, etc.'''
     def __init__(self, env, caller):
         OdfParser.__init__(self, env, caller)
-        self.res = u''
+        self.res = ''
         self.inAnnotation = False # Are we parsing an annotation ?
         self.textEncountered = False # Within an annotation, have we already
         # met a text ?
@@ -58,7 +58,7 @@ class AnnotationsRemover(OdfParser):
                     self.ignore = True
         if not self.ignore:
             self.res += '<%s' % elem
-            for attrName, attrValue in attrs.items():
+            for attrName, attrValue in list(attrs.items()):
                 self.res += ' %s="%s"' % (attrName, attrValue)
             self.res += '>'
     def endElement(self, elem):
@@ -93,12 +93,12 @@ class Test(appy.shared.test.Test):
         if not os.path.exists(contextPy):
             raise TesterError(CONTEXT_NOT_FOUND % contextPy)
         contextPkg = 'appy.pod.test.contexts.%s' % contextName
-        exec 'import %s' % contextPkg
-        exec 'context = dir(%s)' % contextPkg
+        exec('import %s' % contextPkg)
+        exec('context = dir(%s)' % contextPkg)
         res = {}
         for elem in context:
             if not elem.startswith('__'):
-                exec 'res[elem] = %s.%s' % (contextPkg, elem)
+                exec('res[elem] = %s.%s' % (contextPkg, elem))
         return res
 
     def do(self):
diff --git a/pod/test/contexts/ForCell6.py b/pod/test/contexts/ForCell6.py
index 7a11142..f08e973 100644
--- a/pod/test/contexts/ForCell6.py
+++ b/pod/test/contexts/ForCell6.py
@@ -1,6 +1,6 @@
 class Student:
     def __init__(self, **kwargs):
-        for k, v in kwargs.iteritems():
+        for k, v in kwargs.items():
             setattr(self, k, v)
 
 students = [
diff --git a/pod/xhtml2odt.py b/pod/xhtml2odt.py
index b33f09e..9519998 100644
--- a/pod/xhtml2odt.py
+++ b/pod/xhtml2odt.py
@@ -47,7 +47,7 @@ class HtmlElement:
         # but for a strange reason those attrs are back to None (probably for
         # performance reasons they become inaccessible after a while).
         self.classAttr = None
-        if attrs.has_key('class'):
+        if 'class' in attrs:
             self.classAttr = attrs['class']
         self.tagsToReopen = [] # When the HTML element corresponding to self
         # is completely dumped, if there was a problem related to tags
@@ -58,7 +58,7 @@ class HtmlElement:
         # to self, we may need to close other tags (ie closing a paragraph
         # before closing a cell). This list contains HtmlElement instances.
         self.elemType = self.elem
-        if self.elemTypes.has_key(self.elem):
+        if self.elem in self.elemTypes:
             self.elemType = self.elemTypes[self.elem]
         # If a conflict occurs on this element, we will note it.
         self.isConflictual = False
@@ -71,7 +71,7 @@ class HtmlElement:
     def getOdfTag(self, env):
         '''Gets the raw ODF tag that corresponds to me'''
         res = ''
-        if HTML_2_ODT.has_key(self.elem):
+        if self.elem in HTML_2_ODT:
             res += '%s:%s' % (env.textNs, HTML_2_ODT[self.elem])
         elif self.elem == 'a':
             res += '%s:a' % env.textNs
@@ -216,8 +216,8 @@ class HtmlTable:
         elems = str(time.time()).split('.')
         self.name= 'AppyTable%s%s%d' % (elems[0],elems[1],random.randint(1,100))
         self.styleNs = env.ns[OdfEnvironment.NS_STYLE]
-        self.res = u'' # The sub-buffer
-        self.tempRes = u'' # The temporary sub-buffer, into which we will
+        self.res = '' # The sub-buffer
+        self.tempRes = '' # The temporary sub-buffer, into which we will
         # dump all table sub-elements, until we encounter the end of the first
         # row. Then, we will know how much columns are defined in the table;
         # we will dump columns declarations into self.res and dump self.tempRes
@@ -294,8 +294,8 @@ class XhtmlEnvironment(XmlEnvironment):
         XmlEnvironment.__init__(self)
         self.renderer = renderer
         self.ns = renderer.currentParser.env.namespaces
-        self.res = u''
-        self.currentContent = u''
+        self.res = ''
+        self.currentContent = ''
         self.currentElements = [] # Stack of currently walked elements
         self.currentLists = [] # Stack of currently walked lists (ul or ol)
         self.currentTables = [] # Stack of currently walked tables
@@ -349,7 +349,7 @@ class XhtmlEnvironment(XmlEnvironment):
             # Dump and reinitialize the current content
             contentSize = len(self.currentContent)
             self.dumpString(escapeXml(self.currentContent))
-            self.currentContent = u''
+            self.currentContent = ''
         # If we are within a table cell, update the total size of cell content
         if not contentSize: return
         if self.currentTables and self.currentTables[-1].inCell:
@@ -363,7 +363,7 @@ class XhtmlEnvironment(XmlEnvironment):
         styleName = None
         if odtStyle:
             styleName = odtStyle.name
-        elif DEFAULT_ODT_STYLES.has_key(htmlElem.elem):
+        elif htmlElem.elem in DEFAULT_ODT_STYLES:
             styleName = DEFAULT_ODT_STYLES[htmlElem.elem]
         res = ''
         if styleName:
@@ -458,7 +458,7 @@ class XhtmlEnvironment(XmlEnvironment):
         elif elem in TABLE_CELL_TAGS:
             # Determine colspan
             colspan = 1
-            if attrs.has_key('colspan'): colspan = int(attrs['colspan'])
+            if 'colspan' in attrs: colspan = int(attrs['colspan'])
             table = self.currentTables[-1]
             table.inCell = colspan
             table.cellIndex += colspan
@@ -503,7 +503,7 @@ class XhtmlEnvironment(XmlEnvironment):
                     table.res+= '<%s:table-column %s:style-name="%s.%d"/>' % \
                                 (self.tableNs, self.tableNs, table.name, i)
                 table.res += table.tempRes
-                table.tempRes = u''
+                table.tempRes = ''
         elif elem in TABLE_CELL_TAGS:
             # Update attr "columnContentSizes" of the currently parsed table,
             # excepted if the cell spans several columns.
@@ -535,7 +535,7 @@ class XhtmlParser(XmlParser):
         resAttrs = attrs
         if attrs:
             resAttrs = {}
-            for attrName in attrs.keys():
+            for attrName in list(attrs.keys()):
                 resAttrs[attrName.lower()] = attrs[attrName]
         if attrs == None:
             return resElem
@@ -548,11 +548,11 @@ class XhtmlParser(XmlParser):
         currentElem = e.onElementStart(elem, attrs)
         odfTag = currentElem.getOdfTag(e)
 
-        if HTML_2_ODT.has_key(elem):
+        if elem in HTML_2_ODT:
             e.dumpStyledElement(currentElem, odfTag, attrs)
         elif elem == 'a':
             e.dumpString('<%s %s:type="simple"' % (odfTag, e.linkNs))
-            if attrs.has_key('href'):
+            if 'href' in attrs:
                 e.dumpString(' %s:href="%s"' % (e.linkNs,
                                                 escapeXml(attrs['href'])))
             e.dumpString('>')
@@ -577,13 +577,13 @@ class XhtmlParser(XmlParser):
         elif elem in TABLE_CELL_TAGS:
             e.dumpString('<%s %s:style-name="%s"' % \
                 (odfTag, e.tableNs, DEFAULT_ODT_STYLES[elem]))
-            if attrs.has_key('colspan'):
+            if 'colspan' in attrs:
                 e.dumpString(' %s:number-columns-spanned="%s"' % \
                              (e.tableNs, attrs['colspan']))
             e.dumpString('>')
         elif elem == 'img':
             style = None
-            if attrs.has_key('style'): style = attrs['style']
+            if 'style' in attrs: style = attrs['style']
             imgCode = e.renderer.importDocument(at=attrs['src'],
                                                 wrapInPara=False, style=style)
             e.dumpString(imgCode)
diff --git a/px/__init__.py b/px/__init__.py
index 96bab94..c449334 100644
--- a/px/__init__.py
+++ b/px/__init__.py
@@ -4,7 +4,7 @@
 
 # ------------------------------------------------------------------------------
 import xml.sax
-from px_parser import PxParser, PxEnvironment
+from .px_parser import PxParser, PxEnvironment
 from appy.pod.buffers import MemoryBuffer
 from appy.shared.xml_parser import xmlPrologue, xhtmlPrologue
 
@@ -18,7 +18,7 @@ class Px:
     xhtmlPrologue = xhtmlPrologue
 
     def __init__(self, content, isFileName=False, partial=True,
-                 template=None, hook=None, prologue=None, unicode=True):
+                 template=None, hook=None, prologue=None, str=True):
         '''p_content is the PX code, as a string, or a file name if p_isFileName
            is True. If this code represents a complete XML file, p_partial is
            False. Else, we must surround p_content with a root tag to be able
@@ -49,7 +49,7 @@ class Px:
         # Is there some (XML, XHTML...) prologue to dump?
         self.prologue = prologue
         # Will the result be unicode or str?
-        self.unicode = unicode
+        self.str = str
         self.parse()
 
     def parse(self):
@@ -64,7 +64,7 @@ class Px:
         # produce a tree of memory buffers.
         try:
             self.parser.parse(self.content)
-        except xml.sax.SAXParseException, spe:
+        except xml.sax.SAXParseException as spe:
             self.completeErrorMessage(spe)
             raise spe
 
@@ -110,7 +110,7 @@ class Px:
             res = result.content
             if self.prologue:
                 res = self.prologue + res
-            if not self.unicode:
+            if not self.str:
                 res = res.encode('utf-8')
             return res
 
diff --git a/px/px_parser.py b/px/px_parser.py
index 2df697d..2878d48 100644
--- a/px/px_parser.py
+++ b/px/px_parser.py
@@ -66,7 +66,7 @@ class PxParser(XmlParser):
         # See if we have a PX attribute among p_attrs.
         found = False
         for name in self.pxAttributes:
-            if attrs.has_key(name):
+            if name in attrs:
                 if not found:
                     # This is the first PX attr we find.
                     # Create a sub-buffer with an action.
@@ -87,7 +87,7 @@ class PxParser(XmlParser):
             hook = None
             ignorableAttrs = self.pxAttributes
             for name in self.noDumpTags:
-                if attrs.has_key(name) and attrs[name].startswith(':'):
+                if name in attrs and attrs[name].startswith(':'):
                     hook = (name, attrs[name][1:])
                     ignorableAttrs += (name,)
                     break
diff --git a/shared/__init__.py b/shared/__init__.py
index 48b9596..c71c320 100644
--- a/shared/__init__.py
+++ b/shared/__init__.py
@@ -50,12 +50,12 @@ class UnicodeBuffer:
         self.buffer = []
     def write(self, s):
         if s == None: return
-        if isinstance(s, unicode):
+        if isinstance(s, str):
             self.buffer.append(s)
         elif isinstance(s, str):
             self.buffer.append(s.decode('utf-8'))
         else:
-            self.buffer.append(unicode(s))
+            self.buffer.append(str(s))
     def getValue(self):
-        return u''.join(self.buffer)
+        return ''.join(self.buffer)
 # ------------------------------------------------------------------------------
diff --git a/shared/csv_parser.py b/shared/csv_parser.py
index 7726207..1347cc7 100644
--- a/shared/csv_parser.py
+++ b/shared/csv_parser.py
@@ -109,18 +109,18 @@ class CsvParser:
     def convertValue(self, value, basicType):
         '''Converts the atomic p_value which is a string into some other atomic
            Python type specified in p_basicType (int, float, ...).'''
-        if (basicType != str) and (basicType != unicode):
+        if (basicType != str) and (basicType != str):
             try:
-                exec 'res = %s' % str(value)
-            except SyntaxError, se:
+                exec('res = %s' % str(value))
+            except SyntaxError as se:
                 res = None
         else:   
             try:
-                exec 'res = """%s"""' % str(value)
-            except SyntaxError, se:
+                exec('res = """%s"""' % str(value))
+            except SyntaxError as se:
                 try:
-                    exec "res = '''%s'''" % str(value)
-                except SyntaxError, se:
+                    exec("res = '''%s'''" % str(value))
+                except SyntaxError as se:
                     res = None
         return res
 
@@ -183,7 +183,7 @@ class CsvParser:
                 self.res.append(lineObject)
         f.close()
         # The second pass resolves the p_references if any
-        for attrName, refInfo in self.references.iteritems():
+        for attrName, refInfo in self.references.items():
             if attrName in self.attributes:
                 # Replace ID with real object from p_references
                 for obj in self.res:
@@ -228,7 +228,7 @@ class CsvMarshaller:
 
     def marshallValue(self, field, value):
         '''Produces a version of p_value that can be dumped in a CSV file.'''
-        if isinstance(value, basestring):
+        if isinstance(value, str):
             # Format the string as a one-line CSV-ready value
             res = self.marshallString(value)
         elif type(value) in sequenceTypes:
diff --git a/shared/dav.py b/shared/dav.py
index 42e63f6..41c043a 100644
--- a/shared/dav.py
+++ b/shared/dav.py
@@ -1,6 +1,6 @@
 # ------------------------------------------------------------------------------
-import os, re, httplib, sys, stat, urlparse, time, socket, xml.sax
-import urllib
+import os, re, http.client, sys, stat, urllib.parse, time, socket, xml.sax
+from urllib.parse import quote
 from StringIO import StringIO
 from mimetypes import guess_type
 from base64 import encodestring
@@ -19,12 +19,12 @@ class FormDataEncoder:
 
     def marshalValue(self, name, value):
         if isinstance(value, basestring):
-            return '%s=%s' % (name, urllib.quote(str(value)))
+            return '%s=%s' % (name, quote(str(value)))
         elif isinstance(value, float):
             return '%s:float=%s' % (name, value)
         elif isinstance(value, int):
             return '%s:int=%s' % (name, value)
-        elif isinstance(value, long):
+        elif isinstance(value, int):
             res = '%s:long=%s' % (name, value)
             if res[-1] == 'L':
                 res = res[:-1]
@@ -101,8 +101,8 @@ class HttpResponse:
            redirect the user to if self.code is 302, or will unmarshall XML
            data into Python objects.'''
         if self.code == 302:
-            return urlparse.urlparse(self.headers['location'])[2]
-        elif self.headers.has_key('content-type'):
+            return urllib.parse.urlparse(self.headers['location'])[2]
+        elif 'content-type' in self.headers:
             contentType = self.extractContentType(self.headers['content-type'])
             for xmlHeader in self.xmlHeaders:
                 if contentType.startswith(xmlHeader):
@@ -116,7 +116,7 @@ class HttpResponse:
                             raise ResourceError('Distant server exception: ' \
                                                 '%s' % res)
                         return res
-                    except xml.sax.SAXParseException, se:
+                    except xml.sax.SAXParseException as se:
                         raise ResourceError('Invalid XML response (%s)'%str(se))
 
 # ------------------------------------------------------------------------------
@@ -158,7 +158,7 @@ class Resource:
     def updateHeaders(self, headers):
         # Add credentials if present
         if not (self.username and self.password): return
-        if headers.has_key('Authorization'): return
+        if 'Authorization' in headers: return
         credentials = '%s:%s' % (self.username, self.password)
         credentials = credentials.replace('\012', '')
         headers['Authorization'] = "Basic %s" % encodestring(credentials)
@@ -170,19 +170,19 @@ class Resource:
 
     def send(self, method, uri, body=None, headers={}, bodyType=None):
         '''Sends a HTTP request with p_method, for p_uri.'''
-        conn = httplib.HTTPConnection(self.host, self.port)
+        conn = http.client.HTTPConnection(self.host, self.port)
         try:
             conn.connect()
-        except socket.gaierror, sge:
+        except socket.gaierror as sge:
             raise ResourceError('Check your Internet connection (%s)'% str(sge))
-        except socket.error, se:
+        except socket.error as se:
             raise ResourceError('Connection error (%s)' % str(se))
         # Tell what kind of HTTP request it will be.
         conn.putrequest(method, uri, skip_host=True)
         # Add HTTP headers
         self.updateHeaders(headers)
         if self.headers: headers.update(self.headers)
-        for n, v in headers.items(): conn.putheader(n, v)
+        for n, v in list(headers.items()): conn.putheader(n, v)
         conn.endheaders()
         # Add HTTP body
         if body:
diff --git a/shared/diff.py b/shared/diff.py
index ca2ec2b..a836f7a 100644
--- a/shared/diff.py
+++ b/shared/diff.py
@@ -250,7 +250,7 @@ class HtmlDiff:
     deleteStyle = 'color: red; text-decoration: line-through; cursor: help'
 
     def __init__(self, old, new,
-                 insertMsg=u'Inserted text', deleteMsg=u'Deleted text',
+                 insertMsg='Inserted text', deleteMsg='Deleted text',
                  insertCss=None, deleteCss=None, insertName='insert',
                  deleteName='delete', diffRatio=0.7):
         # p_old and p_new are strings containing chunks of HTML. If they are not
@@ -306,24 +306,24 @@ class HtmlDiff:
         else: tag = 'span'
         # What message will it show in its 'title' attribute?
         if not msg:
-            exec 'msg = self.%sMsg' % type
+            exec('msg = self.%sMsg' % type)
         # What CSS class (or, if none, tag-specific style) will be used ?
-        exec 'cssClass = self.%sCss' % type
+        exec('cssClass = self.%sCss' % type)
         if cssClass:
             style = 'class="%s"' % cssClass
         else:
-            exec 'style = self.%sStyle' % type
+            exec('style = self.%sStyle' % type)
             style = 'style="%s"' % style
         # The 'name' attribute of the tag indicates the type of the update.
-        exec 'tagName = self.%sName' % type
+        exec('tagName = self.%sName' % type)
         # The idea is: if there are several lines, every line must be surrounded
         # by a tag. This way, we know that a surrounding tag can't span several
         # lines, which is a prerequisite for managing cumulative diffs.
         if sep == ' ':
-            if not isinstance(seq, basestring):
+            if not isinstance(seq, str):
                 seq = sep.join(seq)
             sep = ''
-        if isinstance(seq, basestring):
+        if isinstance(seq, str):
             return '%s<%s name="%s" %s title="%s">%s</%s>%s' % \
                    (sep, tag, tagName, style, msg, seq, tag, sep)
         else:
@@ -592,7 +592,7 @@ class HtmlDiff:
                     try:
                         merger = Merger(lineA, add, previousDiffsA, self)
                         add = merger.merge()
-                    except Merger.MergeError, e:
+                    except Merger.MergeError as e:
                         # The merge algorithm has made a burn out. Simplify and
                         # consider lineA has having been completely deleted and
                         # lineB has completely inserted.
diff --git a/shared/ldap_connector.py b/shared/ldap_connector.py
index e43f2cd..772853f 100644
--- a/shared/ldap_connector.py
+++ b/shared/ldap_connector.py
@@ -239,14 +239,14 @@ class LdapConnector:
             self.server = ldap.initialize(self.serverUri)
             self.server.simple_bind_s(login, password)
             return True, None
-        except AttributeError, ae:
+        except AttributeError as ae:
             # When the ldap module is not there, trying to catch ldap.LDAPError
             # will raise an error.
             message = str(ae)
             self.log('Ldap connect error with login %s (%s).' % \
                      (login, message))
             return False, message
-        except ldap.LDAPError, le:
+        except ldap.LDAPError as le:
             message = str(le)
             self.log('%s: connect error with login %s (%s).' % \
                      (self.serverUri, login, message))
@@ -275,7 +275,7 @@ class LdapConnector:
                         timeout=self.timeout)
                 except ldap.TIMEOUT:
                     pass
-        except ldap.LDAPError, le:
+        except ldap.LDAPError as le:
             self.log('LDAP query error %s: %s' % \
                      (le.__class__.__name__, str(le)))
 # ------------------------------------------------------------------------------
diff --git a/shared/packaging.py b/shared/packaging.py
index 5e5d61b..c79cd3c 100644
--- a/shared/packaging.py
+++ b/shared/packaging.py
@@ -160,20 +160,20 @@ class Debianizer:
             name = '%s/%sctl' % (binFolder, self.appNameLower)
             f = file(name, 'w')
             f.write(appCtl % self.appNameLower)
-            os.chmod(name, 0744) # Make it executable by owner.
+            os.chmod(name, 0o744) # Make it executable by owner.
             f.close()
             # <app>run
             name = '%s/%srun' % (binFolder, self.appNameLower)
             f = file(name, 'w')
             f.write(appRun % self.appNameLower)
-            os.chmod(name, 0744) # Make it executable by owner.
+            os.chmod(name, 0o744) # Make it executable by owner.
             f.close()
             # startoo
             name = '%s/startoo' % binFolder
             f = file(name, 'w')
             f.write(ooStart)
             f.close()
-            os.chmod(name, 0744) # Make it executable by owner.
+            os.chmod(name, 0o744) # Make it executable by owner.
             # /var/lib/<app> (will store Data.fs, lock files, etc)
             varLibFolder = j(debFolder, 'var', 'lib', self.appNameLower)
             os.makedirs(varLibFolder)
@@ -208,7 +208,7 @@ class Debianizer:
                                   'application.' % n, '%sctl start' % n,
                                   '%sctl restart' % n, '%sctl stop' % n))
             f.close()
-            os.chmod(name, 0744) # Make it executable by owner.
+            os.chmod(name, 0o744) # Make it executable by owner.
             # /etc/init.d/oo (start OpenOffice at boot time)
             name = '%s/oo' % initdFolder
             f = file(name, 'w')
@@ -216,7 +216,7 @@ class Debianizer:
                                   'startoo', 'startoo', "#Can't stop OO."))
             f.write('\n')
             f.close()
-            os.chmod(name, 0744) # Make it executable by owner.
+            os.chmod(name, 0o744) # Make it executable by owner.
         # Get the size of the app, in Kb.
         os.chdir(tempFolder)
         cmd = subprocess.Popen(['du', '-b', '-s', 'debian'],
diff --git a/shared/rtf.py b/shared/rtf.py
index 352287b..be9ddf6 100644
--- a/shared/rtf.py
+++ b/shared/rtf.py
@@ -25,8 +25,8 @@
      be strictly greater than 1.'''
 
 # -----------------------------------------------------------------------------
-import re, sys, UserList, UserDict
-from StringIO import StringIO
+import re, sys, collections, UserDict
+from io import StringIO
 
 # -----------------------------------------------------------------------------
 class ParserError(Exception): pass
@@ -69,7 +69,7 @@ LIST_VALUE_ERROR = 'Value "%s" is malformed: within it, %s. You should check ' \
 
 # -----------------------------------------------------------------------------
 class Type:
-    basicTypes = {'f': float, 'i':int, 'g':long, 'b':bool}
+    basicTypes = {'f': float, 'i':int, 'g':int, 'b':bool}
     separators = ['-', ';', ',', ':']
     def __init__(self, typeDecl):
         self.basicType = None # The python basic type
@@ -85,12 +85,12 @@ class Type:
                 self.listNumber += 1
             else:
                 # Get the basic type
-                if not (char in Type.basicTypes.keys()):
+                if not (char in list(Type.basicTypes.keys())):
                     raise TypeError(BASIC_TYPE_ERROR % char)
                 self.basicType = Type.basicTypes[char]
                 break
         if not self.basicType:
-            self.basicType = unicode
+            self.basicType = str
     def convertBasicValue(self, value):
         try:
             return self.basicType(value.strip())
@@ -136,7 +136,7 @@ class Type:
             elif not resIsComplete:
                 try:
                     res = self.convertListItem(value, separators)
-                except TypeError, te:
+                except TypeError as te:
                     raise TypeError(LIST_VALUE_ERROR % (value, te, self.name))
         return res
     def convertListItem(self, stringItem, remainingSeps):
@@ -161,9 +161,9 @@ class Type:
         return self.name
 
 # -----------------------------------------------------------------------------
-class Table(UserList.UserList):
+class Table(collections.UserList):
     def __init__(self):
-        UserList.UserList.__init__(self)
+        collections.UserList.__init__(self)
         self.name = None
         self.parent = None
         self.parentRow = None
@@ -213,7 +213,7 @@ class TableRow(UserDict.UserDict):
         via the parent table self.table.'''
         keyError = False
         t = self.table
-        if self.has_key(key):
+        if key in self:
             res = UserDict.UserDict.__getitem__(self, key)
         else:
             # Get the parent row
@@ -259,9 +259,9 @@ class TableRow(UserDict.UserDict):
 # -----------------------------------------------------------------------------
 class NameResolver:
     def resolveNames(self, tables):
-        for tableName, table in tables.iteritems():
+        for tableName, table in tables.items():
             if table.parent:
-                if not tables.has_key(table.parent):
+                if table.parent not in tables:
                     raise ParserError(PARENT_NOT_FOUND %
                                           (table.parent, table.name))
                 table.parent = tables[table.parent]
@@ -330,10 +330,10 @@ class TableParser:
     def manageSpecialChar(self):
         specialChar = int(self.specialCharBuffer)
         self.specialCharBuffer = ''
-        if self.specialChars.has_key(specialChar):
+        if specialChar in self.specialChars:
             self.contentBuffer.write(self.specialChars[specialChar])
         else:
-            print('Warning: char %d not known.' % specialChar)
+            print(('Warning: char %d not known.' % specialChar))
         self.state = TableParser.READING_CONTENT
     def bufferize(self, char):
         if self.state == TableParser.READING_CONTROL_WORD:
@@ -403,7 +403,7 @@ class TableParser:
                 columnNames.append(name.strip())
                 try:
                     columnTypes.append(Type(typeDecl.strip()))
-                except TypeError, te:
+                except TypeError as te:
                     raise ParserError(TYPE_ERROR %
                                       (header, self.currentTableName, te))
             else:
@@ -449,7 +449,7 @@ class TableParser:
                 if columnType:
                     try:
                         columnValue = columnType.convertValue(columnValue)
-                    except TypeError, te:
+                    except TypeError as te:
                         raise ParserError(VALUE_ERROR %
                                           (columnName, self.currentTableName,
                                            te))
@@ -496,7 +496,7 @@ class RtfTablesParser:
 # -----------------------------------------------------------------------------
 if __name__ =='__main__':
     tables = RtfTablesParser("Tests.rtf").parse()
-    for key, item in tables.iteritems():
-        print('Table %s' % key)
+    for key, item in tables.items():
+        print(('Table %s' % key))
         print(item)
 # -----------------------------------------------------------------------------
diff --git a/shared/sap.py b/shared/sap.py
index b8c747b..5c5859c 100644
--- a/shared/sap.py
+++ b/shared/sap.py
@@ -74,7 +74,7 @@ class Sap:
         try:
             self.sap = pysap.Rfc_connection(conn_string = params)
             self.sap.open()
-        except pysap.BaseSapRfcError, se:
+        except pysap.BaseSapRfcError as se:
             # Put in the error message the connection string without the
             # password.
             connNoPasswd = params[:params.index('PASSWD')] + 'PASSWD=********'
@@ -84,7 +84,7 @@ class Sap:
         '''Create a struct corresponding to SAP/C structure definition
            p_structDef and fills it with dict p_userData.'''
         res = structDef()
-        for name, value in userData.iteritems():
+        for name, value in userData.items():
             if name not in structDef._sfield_names_:
                 raise SapError(SAP_STRUCT_ELEM_NOT_FOUND % (paramName, name))
             sapType = structDef._sfield_sap_types_[name]
@@ -93,7 +93,7 @@ class Sap:
                 sType = '%s%d' % (sapType[0], sapType[1])
                 # "None" value is tolerated.
                 if value == None: value = ''
-                if not isinstance(value, basestring):
+                if not isinstance(value, str):
                     raise SapError(
                         SAP_STRING_REQUIRED % (name, paramName, sType))
                 if len(value) > sapType[1]:
@@ -113,7 +113,7 @@ class Sap:
                 functionName = self.functionName
             function = self.sap.get_interface(functionName)
             # Specify the parameters
-            for name, value in params.iteritems():
+            for name, value in params.items():
                 if type(value) == dict:
                     # The param corresponds to a SAP/C "struct"
                     v = self.createStructure(
@@ -140,7 +140,7 @@ class Sap:
                 function[name] = v
             # Call the function
             function()
-        except pysap.BaseSapRfcError, se:
+        except pysap.BaseSapRfcError as se:
             raise SapError(SAP_FUNCTION_ERROR % (functionName, str(se)))
         return SapResult(function)
 
@@ -198,10 +198,10 @@ class Sap:
                         self.sap.get_structure(typeName)
                         res += '%s\n%s\n\n' % \
                             (typeName, self.getTypeInfo(typeName))
-                    except pysap.BaseSapRfcError, ee:
+                    except pysap.BaseSapRfcError as ee:
                         pass
             return res
-        except pysap.BaseSapRfcError, se:
+        except pysap.BaseSapRfcError as se:
             if se.value == 'FU_NOT_FOUND':
                 raise SapError(SAP_FUNCTION_NOT_FOUND % (functionName))
             else:
@@ -229,6 +229,6 @@ class Sap:
         '''Disconnects from SAP.'''
         try:
             self.sap.close()
-        except pysap.BaseSapRfcError, se:
+        except pysap.BaseSapRfcError as se:
             raise SapError(SAP_DISCONNECT_ERROR % str(se))
 # ------------------------------------------------------------------------------
diff --git a/shared/test.py b/shared/test.py
index dacb93b..d5c9863 100644
--- a/shared/test.py
+++ b/shared/test.py
@@ -177,7 +177,7 @@ class Tester:
            (not isinstance(flavours, tuple)):
             raise TesterError(FLAVOURS_NOT_LIST)
         for flavour in flavours:
-            if not isinstance(flavour, basestring):
+            if not isinstance(flavour, str):
                 raise TesterError(FLAVOUR_NOT_STRING)
         self.flavours = flavours
         self.flavour = None
@@ -198,7 +198,7 @@ class Tester:
         if self.flavour:
             ext = '.%s' % self.flavour
         configTableName = 'Configuration%s' % ext
-        if self.tables.has_key(configTableName):
+        if configTableName in self.tables:
             self.config = self.tables[configTableName].asDict()
         self.tempFolder = os.path.join(self.testFolder, 'temp')
         if os.path.exists(self.tempFolder):
@@ -249,11 +249,11 @@ class Tester:
                     self.report.say('Test successful.\n')
                     self.nbOfSuccesses += 1
     def run(self):
-        assert self.tables.has_key('TestSuites'), \
+        assert 'TestSuites' in self.tables, \
                TesterError(MAIN_TABLE_NOT_FOUND % self.testPlan)
         for testSuite in self.tables['TestSuites']:
-            if (not testSuite.has_key('Name')) or \
-               (not testSuite.has_key('Description')):
+            if ('Name' not in testSuite) or \
+               ('Description' not in testSuite):
                 raise TesterError(MAIN_TABLE_MALFORMED)
             if testSuite['Name'].startswith('_'):
                 tsName = testSuite['Name'][1:]
@@ -261,8 +261,8 @@ class Tester:
             else:
                 tsName = testSuite['Name']
                 tsIgnored = False
-            assert self.tables.has_key('%s.descriptions' % tsName) \
-                   and self.tables.has_key('%s.data' % tsName), \
+            assert '%s.descriptions' % tsName in self.tables \
+                   and '%s.data' % tsName in self.tables, \
                    TesterError(TEST_SUITE_NOT_FOUND % (tsName, tsName))
             assert len(self.tables['%s.descriptions' % tsName]) == \
                    len(self.tables['%s.data' % tsName]), \
diff --git a/shared/utils.py b/shared/utils.py
index 9b68680..daef14a 100644
--- a/shared/utils.py
+++ b/shared/utils.py
@@ -44,7 +44,7 @@ class FolderDeleter:
                     dirName = os.path.dirname(dirName)
                 else:
                     break
-            except OSError, oe:
+            except OSError:
                 break
 
 # ------------------------------------------------------------------------------
@@ -53,7 +53,7 @@ def cleanFolder(folder, exts=extsToClean, folders=(), verbose=False):
     '''This function allows to remove, in p_folder and subfolders, any file
        whose extension is in p_exts, and any folder whose name is in
        p_folders.'''
-    if verbose: print('Cleaning folder %s...' % folder)
+    if verbose: print(('Cleaning folder %s...' % folder))
     # Remove files with an extension listed in p_exts
     if exts:
         for root, dirs, files in os.walk(folder):
@@ -61,7 +61,7 @@ def cleanFolder(folder, exts=extsToClean, folders=(), verbose=False):
                 ext = os.path.splitext(fileName)[1]
                 if (ext in exts) or ext.endswith('~'):
                     fileToRemove = os.path.join(root, fileName)
-                    if verbose: print('Removing file %s...' % fileToRemove)
+                    if verbose: print(('Removing file %s...' % fileToRemove))
                     os.remove(fileToRemove)
     # Remove folders whose names are in p_folders.
     if folders:
@@ -69,7 +69,7 @@ def cleanFolder(folder, exts=extsToClean, folders=(), verbose=False):
             for folderName in dirs:
                 if folderName in folders:
                     toDelete = os.path.join(root, folderName)
-                    if verbose: print('Removing folder %s...' % toDelete)
+                    if verbose: print(('Removing folder %s...' % toDelete))
                     FolderDeleter.delete(toDelete)
 
 # ------------------------------------------------------------------------------
@@ -142,14 +142,14 @@ def copyData(data, target, targetMethod, type='string', encoding=None,
             dump(encodeData(chunk, encoding))
     elif type == 'zope':
         # A OFS.Image.File instance can be split into several chunks
-        if isinstance(data.data, basestring): # One chunk
+        if isinstance(data.data, str): # One chunk
             dump(encodeData(data.data, encoding))
         else:
             # Several chunks
             data = data.data
             while data is not None:
                 dump(encodeData(data.data, encoding))
-                data = data.next
+                data = data.__next__
 
 # ------------------------------------------------------------------------------
 def splitList(l, sub):
@@ -222,12 +222,12 @@ def getOsTempFolder():
     tmp = '/tmp'
     if os.path.exists(tmp) and os.path.isdir(tmp):
         res = tmp
-    elif os.environ.has_key('TMP'):
+    elif 'TMP' in os.environ:
         res = os.environ['TMP']
-    elif os.environ.has_key('TEMP'):
+    elif 'TEMP' in os.environ:
         res = os.environ['TEMP']
     else:
-        raise "Sorry, I can't find a temp folder on your machine."
+        raise Exception("Sorry, I can't find a temp folder on your machine.")
     return res
 
 def getTempFileName(prefix='', extension=''):
@@ -273,10 +273,10 @@ def normalizeString(s, usage='fileName'):
         except UnicodeDecodeError:
             # Another encoding may be in use
             s = s.decode('latin-1')
-    elif not isinstance(s, unicode): s = unicode(s)
+    elif not isinstance(s, str): s = str(s)
     # For extracted text, replace any unwanted char with a blank
     if usage == 'extractedText':
-        res = u''
+        res = ''
         for char in s:
             if char not in extractIgnore: res += char
             else: res += ' '
@@ -291,7 +291,7 @@ def normalizeString(s, usage='fileName'):
         for char in s:
             if char not in fileNameIgnore: res += char
     elif usage.startswith('alpha'):
-        exec 'rex = %sRex' % usage
+        exec('rex = %sRex' % usage)
         res = ''
         for char in s:
             if rex.match(char): res += char
@@ -319,7 +319,7 @@ def keepDigits(s):
 def getStringDict(d):
     '''Gets the string literal corresponding to dict p_d.'''
     res = []
-    for k, v in d.iteritems():
+    for k, v in d.items():
         if type(v) not in sequenceTypes:
             if not isinstance(k, basestring): k = str(k)
             if not isinstance(v, basestring): v = str(v)
@@ -386,7 +386,7 @@ def formatNumber(n, sep=',', precision=2, tsep=' '):
 # ------------------------------------------------------------------------------
 def lower(s):
     '''French-accents-aware variant of string.lower.'''
-    isUnicode = isinstance(s, unicode)
+    isUnicode = isinstance(s, str)
     if not isUnicode: s = s.decode('utf-8')
     res = s.lower()
     if not isUnicode: res = res.encode('utf-8')
@@ -394,14 +394,14 @@ def lower(s):
 
 def upper(s):
     '''French-accents-aware variant of string.upper.'''
-    isUnicode = isinstance(s, unicode)
+    isUnicode = isinstance(s, str)
     if not isUnicode: s = s.decode('utf-8')
     res = s.upper()
     if not isUnicode: res = res.encode('utf-8')
     return res
 
 # ------------------------------------------------------------------------------
-typeLetters = {'b': bool, 'i': int, 'j': long, 'f':float, 's':str, 'u':unicode,
+typeLetters = {'b': bool, 'i': int, 'j': int, 'f':float, 's':str, 'u':str,
                'l': list, 'd': dict}
 caExts = {'py': ('.py', '.vpy', '.cpy'), 'xml': ('.pt', '.cpt', '.xml')}
 
@@ -506,8 +506,8 @@ class CodeAnalysis:
         if not lines: return
         commentRate = (self.commentLines / float(lines)) * 100.0
         blankRate = (self.emptyLines / float(lines)) * 100.0
-        print('%s: %d files, %d lines (%.0f%% comments, %.0f%% blank)' % \
-              (self.name, self.numberOfFiles, lines, commentRate, blankRate))
+        print(('%s: %d files, %d lines (%.0f%% comments, %.0f%% blank)' % \
+              (self.name, self.numberOfFiles, lines, commentRate, blankRate)))
 
 # ------------------------------------------------------------------------------
 class LinesCounter:
@@ -516,7 +516,7 @@ class LinesCounter:
                        '%stemp' % os.sep)
 
     def __init__(self, folderOrModule, excludes=None):
-        if isinstance(folderOrModule, basestring):
+        if isinstance(folderOrModule, str):
             # It is the path of some folder
             self.folder = folderOrModule
         else:
@@ -624,10 +624,10 @@ class FileWrapper:
         if self.content.__class__.__name__ == 'Pdata':
             # The file content is splitted in several chunks.
             f.write(self.content.data)
-            nextPart = self.content.next
+            nextPart = self.content.__next__
             while nextPart:
                 f.write(nextPart.data)
-                nextPart = nextPart.next
+                nextPart = nextPart.__next__
         else:
             # Only one chunk
             f.write(self.content)
diff --git a/shared/xml_parser.py b/shared/xml_parser.py
index 02dcc26..d572668 100644
--- a/shared/xml_parser.py
+++ b/shared/xml_parser.py
@@ -66,9 +66,9 @@ HTML_ENTITIES = {
         'euro':'€', 'nbsp':' ', "rsquo":"'", "lsquo":"'", "ldquo":"'",
         "rdquo":"'", 'ndash': '—', 'mdash': '—', 'oelig':'oe', 'quot': "'",
         'mu': 'µ'}
-import htmlentitydefs
-for k, v in htmlentitydefs.entitydefs.iteritems():
-    if not HTML_ENTITIES.has_key(k) and not XML_ENTITIES.has_key(k):
+import html.entities
+for k, v in html.entities.entitydefs.items():
+    if k not in HTML_ENTITIES and k not in XML_ENTITIES:
         HTML_ENTITIES[k] = ''
 
 def escapeXml(s, format='xml', nsText='text'):
@@ -77,13 +77,13 @@ def escapeXml(s, format='xml', nsText='text'):
        their ODF counterparts. In this case, it is needed to give the name of
        the "text" namespace (p_nsText) as defined in the ODF document where the
        line breaks and tabs must be inserted.'''
-    if isinstance(s, unicode):
-        res = u''
+    if isinstance(s, str):
+        res = ''
     else:
         res = ''
     odf = format == 'odf'
     for c in s:
-        if XML_SPECIAL_CHARS_NO_APOS.has_key(c):
+        if c in XML_SPECIAL_CHARS_NO_APOS:
             # We do not escape 'apos': there is no particular need for that.
             res += XML_SPECIAL_CHARS_NO_APOS[c]
         elif odf and (c == '\n'):
@@ -99,12 +99,12 @@ def escapeXml(s, format='xml', nsText='text'):
 def escapeXhtml(s):
     '''Return p_s, whose XHTML special chars and carriage return chars have
        been replaced with corresponding XHTML entities.'''
-    if isinstance(s, unicode):
-        res = u''
+    if isinstance(s, str):
+        res = ''
     else:
         res = ''
     for c in s:
-        if XML_SPECIAL_CHARS_NO_APOS.has_key(c):
+        if c in XML_SPECIAL_CHARS_NO_APOS:
             res += XML_SPECIAL_CHARS_NO_APOS[c]
         elif c == '\n':
             res += '<br/>'
@@ -144,7 +144,7 @@ class XmlElement:
         res = self.elem
         if self.attrs:
             res += '('
-            for attrName, attrValue in self.attrs.items():
+            for attrName, attrValue in list(self.attrs.items()):
                 res += '%s="%s"' % (attrName, attrValue)
             res += ')'
         return res
@@ -167,7 +167,7 @@ class XmlEnvironment:
         self.parser = None
     def manageNamespaces(self, attrs):
         '''Manages namespaces definitions encountered in p_attrs.'''
-        for attrName, attrValue in attrs.items():
+        for attrName, attrValue in list(attrs.items()):
             if attrName.startswith('xmlns:'):
                 self.namespaces[attrValue] = attrName[6:]
     def ns(self, nsUri):
@@ -221,7 +221,7 @@ class XmlParser(ContentHandler, ErrorHandler):
     def skippedEntity(self, name):
         '''This method is called every time expat does not recognize an entity.
            We provide here support for HTML entities.'''
-        if HTML_ENTITIES.has_key(name):
+        if name in HTML_ENTITIES:
             self.characters(HTML_ENTITIES[name].decode('utf-8'))
         else:
             # Put a question mark instead of raising an exception.
@@ -230,10 +230,10 @@ class XmlParser(ContentHandler, ErrorHandler):
     # ErrorHandler methods ---------------------------------------------------
     def error(self, error):
         if self.raiseOnError: raise error
-        else: print('SAX error %s' % str(error))
+        else: print(('SAX error %s' % str(error)))
     def fatalError(self, error):
         if self.raiseOnError: raise error
-        else: print('SAX fatal error %s' % str(error))
+        else: print(('SAX fatal error %s' % str(error)))
     def warning(self, error): pass
 
     def parse(self, xml, source='string'):
@@ -246,9 +246,9 @@ class XmlParser(ContentHandler, ErrorHandler):
                method will close it.
         '''
         try:
-            from cStringIO import StringIO
+            from io import StringIO
         except ImportError:
-            from StringIO import StringIO
+            from io import StringIO
         self._xml = xml
         self.parser.setContentHandler(self)
         self.parser.setErrorHandler(self)
@@ -333,7 +333,7 @@ class XmlUnmarshaller(XmlParser):
     def convertAttrs(self, attrs):
         '''Converts XML attrs to a dict.'''
         res = {}
-        for k, v in attrs.items():
+        for k, v in list(attrs.items()):
             if ':' in k: # An attr prefixed with a namespace. Remove this.
                 k = k.split(':')[-1]
             res[str(k)] = self.encode(v)
@@ -362,9 +362,9 @@ class XmlUnmarshaller(XmlParser):
         e = XmlParser.startElement(self, elem, attrs)
         # Determine the type of the element.
         elemType = 'unicode' # Default value
-        if attrs.has_key('type'):
+        if 'type' in attrs:
             elemType = attrs['type']
-        elif self.tagTypes.has_key(elem):
+        elif elem in self.tagTypes:
             elemType = self.tagTypes[elem]
         if elemType in self.containerTags:
             # I must create a new container object.
@@ -375,9 +375,9 @@ class XmlUnmarshaller(XmlParser):
             elif elemType == 'dict': newObject = {}
             elif elemType == 'file':
                 newObject = UnmarshalledFile()
-                if attrs.has_key('name'):
+                if 'name' in attrs:
                     newObject.name = self.encode(attrs['name'])
-                if attrs.has_key('mimeType'):
+                if 'mimeType' in attrs:
                     newObject.mimeType = self.encode(attrs['mimeType'])
             else: newObject = Object(**self.convertAttrs(attrs))
             # Store the value on the last container, or on the root object.
@@ -454,17 +454,17 @@ class XmlUnmarshaller(XmlParser):
             if not value: value = None
             else:
                 # If we have a custom converter for values of this type, use it.
-                if self.conversionFunctions.has_key(e.currentBasicType):
+                if e.currentBasicType in self.conversionFunctions:
                     try:
                         value = self.conversionFunctions[e.currentBasicType](
                             value)
-                    except Exception, err:
+                    except Exception as err:
                         raise AppyError(CUSTOM_CONVERSION_ERROR % (
                             e.currentBasicType, value, str(err)))
                 # If not, try a standard conversion
                 elif e.currentBasicType in self.numericTypes:
                     try:
-                        exec 'value = %s' % value
+                        exec('value = %s' % value)
                     except SyntaxError:
                         raise AppyError(CONVERSION_ERROR % (
                             e.currentBasicType, value))
@@ -578,7 +578,7 @@ class XmlMarshaller:
         tagName = self.getTagName(self.rootElementName)
         res.write('<'); res.write(tagName)
         # Dumps namespace definitions if any
-        for prefix, url in self.namespaces.iteritems():
+        for prefix, url in self.namespaces.items():
             if not prefix:
                 pre = 'xmlns' # The default namespace
             else:
@@ -597,7 +597,7 @@ class XmlMarshaller:
             s = s.decode('utf-8')
         # Replace special chars by XML entities
         for c in s:
-            if self.xmlEntities.has_key(c):
+            if c in self.xmlEntities:
                 res.write(self.xmlEntities[c])
             else:
                 res.write(c)
@@ -617,13 +617,13 @@ class XmlMarshaller:
                 # There will be several parts.
                 w(v.data.data.encode('base64'))
                 # Write subsequent parts
-                nextPart = v.data.next
+                nextPart = v.data.__next__
                 nextPartNb = 2
                 while nextPart:
                     w('</%s>' % partTag) # Close the previous part
                     w('<%s type="base64" number="%d">' % (partTag, nextPartNb))
                     w(nextPart.data.encode('base64'))
-                    nextPart = nextPart.next
+                    nextPart = nextPart.__next__
                     nextPartNb += 1
             else:
                 w(v.data.encode('base64'))
@@ -654,7 +654,7 @@ class XmlMarshaller:
 
     def dumpDict(self, res, v):
         '''Dumps the XML version of dict p_v.'''
-        for key, value in v.iteritems():
+        for key, value in v.items():
             res.write('<entry type="object">')
             self.dumpField(res, 'k', key)
             self.dumpField(res, 'v', value)
@@ -681,7 +681,7 @@ class XmlMarshaller:
             # The previous condition must be checked before this one because
             # referred objects may be stored in lists or tuples, too.
             for elem in value: self.dumpField(res, 'e', elem)
-        elif isinstance(value, basestring): self.dumpString(res, value)
+        elif isinstance(value, str): self.dumpString(res, value)
         elif isinstance(value, bool): res.write(self.trueFalse[value])
         elif fieldType == 'object':
             if hasattr(value, 'absolute_url'):
@@ -689,7 +689,7 @@ class XmlMarshaller:
                 res.write(value.absolute_url())
             else:
                 # Dump the entire object content
-                for k, v in value.__dict__.iteritems():
+                for k, v in value.__dict__.items():
                     if not k.startswith('__'):
                         self.dumpField(res, k, v)
                 # Maybe we could add a parameter to the marshaller to know how
@@ -771,7 +771,7 @@ class XmlMarshaller:
             rootTagName = self.dumpRootTag(res, instance)
             # Dump the fields of this root object
             if objectType == 'popo':
-                for fieldName, fieldValue in instance.__dict__.iteritems():
+                for fieldName, fieldValue in instance.__dict__.items():
                     mustDump = False
                     if fieldName in self.fieldsToExclude:
                         mustDump = False
@@ -823,11 +823,11 @@ class XmlMarshaller:
                     histTag = self.getTagName('history')
                     eventTag = self.getTagName('event')
                     res.write('<%s type="list">' % histTag)
-                    key = instance.workflow_history.keys()[0]
+                    key = list(instance.workflow_history.keys())[0]
                     history = instance.workflow_history[key]
                     for event in history:
                         res.write('<%s type="object">' % eventTag)
-                        for k, v in event.iteritems():
+                        for k, v in event.items():
                             self.dumpField(res, k, v)
                         res.write('</%s>' % eventTag)
                     res.write('</%s>' % histTag)
@@ -856,7 +856,7 @@ class XmlHandler(ContentHandler):
        (like dates) from a file that need to be compared to another file.'''
     def __init__(self, xmlTagsToIgnore, xmlAttrsToIgnore):
         ContentHandler.__init__(self)
-        self.res = unicode(xmlPrologue)
+        self.res = str(xmlPrologue)
         self.namespaces = {} # ~{s_namespaceUri:s_namespaceName}~
         self.indentLevel = -1
         self.tabWidth = 3
@@ -891,7 +891,7 @@ class XmlHandler(ContentHandler):
         self.res += '\n' + (' ' * self.indentLevel * self.tabWidth)
     def manageNamespaces(self, attrs):
         '''Manage namespaces definitions encountered in attrs'''
-        for attrName, attrValue in attrs.items():
+        for attrName, attrValue in list(attrs.items()):
             if attrName.startswith('xmlns:'):
                 self.namespaces[attrValue] = attrName[6:]
     def ns(self, nsUri):
@@ -906,7 +906,7 @@ class XmlHandler(ContentHandler):
                 self.indentLevel += 1
                 self.dumpSpaces()
                 self.res += '<%s' % elem
-                attrsNames = attrs.keys()
+                attrsNames = list(attrs.keys())
                 attrsNames.sort()
                 for attrToIgnore in self.attrsToIgnore:
                     if attrToIgnore in attrsNames:
@@ -986,7 +986,7 @@ class XmlComparator:
                     else: print(line)
                 else:
                     if report: report.say(line[:-1], encoding=encoding)
-                    else: print(line[:-1])
+                    else: print((line[:-1]))
                 lastLinePrinted = True
             else:
                 lastLinePrinted = False
@@ -1061,7 +1061,7 @@ class XhtmlCleaner(XmlParser):
         self.env.ignoreContent = False
         try:
             res = self.parse('<x>%s</x>' % s).encode('utf-8')
-        except SAXParseException, e:
+        except SAXParseException as e:
             raise self.Error(str(e))
         return res
 
@@ -1106,7 +1106,7 @@ class XhtmlCleaner(XmlParser):
             prefix = ''
         res = '%s<%s' % (prefix, elem)
         # Include the found attributes, excepted those that must be ignored.
-        for name, value in attrs.items():
+        for name, value in list(attrs.items()):
             if not self.keepStyles:
                 if name in self.attrsToIgnore: continue
                 elif name == 'style':
@@ -1115,7 +1115,7 @@ class XhtmlCleaner(XmlParser):
             res += ' %s="%s"' % (name, value)
         # Include additional attributes if required.
         if elem in self.attrsToAdd:
-            for name, value in self.attrsToAdd[elem].iteritems():
+            for name, value in self.attrsToAdd[elem].items():
                 res += ' %s="%s"' % (name, value)
         # Close the tag if it is a no-end tag
         if elem in self.noEndTags:
@@ -1163,7 +1163,7 @@ class XhtmlCleaner(XmlParser):
             # I give here to lstrip an explicit list of what is to be considered
             # as blank chars, because I do not want unicode NBSP chars to be in
             # this list.
-            toAdd = content.lstrip(u' \n\r\t')
+            toAdd = content.lstrip(' \n\r\t')
         else:
             toAdd = content
         # Re-transform XML special chars to entities.