Add the "provider" concept, let them configure db sessions

more to come...

tailbone/app.py

@@ -2,7 +2,7 @@
 ################################################################################
 #
 #  Rattail -- Retail Software Framework
-#  Copyright © 2010-2020 Lance Edgar
+#  Copyright © 2010-2022 Lance Edgar
 #
 #  This file is part of Rattail.
 #
@@ -45,6 +45,7 @@ import tailbone.db
 from tailbone.auth import TailboneAuthorizationPolicy
 from tailbone.config import csrf_token_name, csrf_header_name
 from tailbone.util import get_effective_theme, get_theme_template_path
+from tailbone.providers import get_all_providers
 
 
 def make_rattail_config(settings):
@@ -115,6 +116,8 @@ def make_pyramid_config(settings, configure_csrf=True):
     """
     Make a Pyramid config object from the given settings.
     """
+    rattail_config = settings['rattail_config']
+
     config = settings.pop('pyramid_config', None)
     if config:
         config.set_root_factory(Root)
@@ -132,7 +135,6 @@ def make_pyramid_config(settings, configure_csrf=True):
 
     # maybe require CSRF token protection
     if configure_csrf:
-        rattail_config = settings['rattail_config']
         config.set_default_csrf_options(require_csrf=True,
                                         token=csrf_token_name(rattail_config),
                                         header=csrf_header_name(rattail_config))
@@ -152,6 +154,11 @@ def make_pyramid_config(settings, configure_csrf=True):
     else:
         config.include('pyramid_retry')
 
+    # configure DB sessions associated with transaction manager
+    providers = get_all_providers(rattail_config)
+    for provider in six.itervalues(providers):
+        provider.configure_db_sessions(rattail_config, config)
+
     # Add some permissions magic.
     config.add_directive('add_tailbone_permission_group', 'tailbone.auth.add_permission_group')
     config.add_directive('add_tailbone_permission', 'tailbone.auth.add_permission')

tailbone/providers.py

@@ -0,0 +1,56 @@
+# -*- coding: utf-8; -*-
+################################################################################
+#
+#  Rattail -- Retail Software Framework
+#  Copyright © 2010-2022 Lance Edgar
+#
+#  This file is part of Rattail.
+#
+#  Rattail is free software: you can redistribute it and/or modify it under the
+#  terms of the GNU General Public License as published by the Free Software
+#  Foundation, either version 3 of the License, or (at your option) any later
+#  version.
+#
+#  Rattail is distributed in the hope that it will be useful, but WITHOUT ANY
+#  WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+#  FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
+#  details.
+#
+#  You should have received a copy of the GNU General Public License along with
+#  Rattail.  If not, see <http://www.gnu.org/licenses/>.
+#
+################################################################################
+"""
+Providers for Tailbone features
+"""
+
+from __future__ import unicode_literals, absolute_import
+
+from rattail.util import load_entry_points
+
+
+class TailboneProvider(object):
+    """
+    Base class for Tailbone providers.  These are responsible for
+    declaring which things a given project makes available to the app.
+    (Or at least the things which should be easily configurable.)
+    """
+
+    def __init__(self, config):
+        self.config = config
+
+    def configure_db_sessions(self, rattail_config, pyramid_config):
+        pass
+
+    def get_provided_views(self):
+        return {}
+
+
+def get_all_providers(config):
+    """
+    Returns a dict of all registered providers.
+    """
+    providers = load_entry_points('tailbone.providers')
+    for key in list(providers):
+        providers[key] = providers[key](config)
+    return providers