Add convenience function for core_office_url() config

rattail_corepos/config.py

@@ -47,3 +47,18 @@ class RattailCOREPOSExtension(ConfigExtension):
         config.coretrans_engines = engines
         config.coretrans_engine = engines.get('default')
         CoreTransSession.configure(bind=config.coretrans_engine)
+
+
+def core_office_url(config, require=False, **kwargs):
+    """
+    Returns the base URL for the CORE Office web app.  Note that this URL will
+    *not* have a trailing slash.
+    """
+    args = ['corepos', 'office.url']
+    if require:
+        url = config.require(*args, **kwargs)
+        return url.rstrip('/')
+    else:
+        url = config.get(*args, **kwargs)
+        if url:
+            return url.rstrip('/')