--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/web/lib/django/contrib/messages/storage/fallback.py	Tue May 25 02:43:45 2010 +0200
@@ -0,0 +1,54 @@
+from django.contrib.messages.storage.base import BaseStorage
+from django.contrib.messages.storage.cookie import CookieStorage
+from django.contrib.messages.storage.session import SessionStorage
+
+class FallbackStorage(BaseStorage):
+    """
+    Tries to store all messages in the first backend, storing any unstored
+    messages in each subsequent backend backend.
+    """
+    storage_classes = (CookieStorage, SessionStorage)
+
+    def __init__(self, *args, **kwargs):
+        super(FallbackStorage, self).__init__(*args, **kwargs)
+        self.storages = [storage_class(*args, **kwargs)
+                         for storage_class in self.storage_classes]
+        self._used_storages = set()
+
+    def _get(self, *args, **kwargs):
+        """
+        Gets a single list of messages from all storage backends.
+        """
+        all_messages = []
+        for storage in self.storages:
+            messages, all_retrieved = storage._get()
+            # If the backend hasn't been used, no more retrieval is necessary.
+            if messages is None:
+                break
+            if messages:
+                self._used_storages.add(storage)
+            all_messages.extend(messages)
+            # If this storage class contained all the messages, no further
+            # retrieval is necessary
+            if all_retrieved:
+                break
+        return all_messages, all_retrieved
+
+    def _store(self, messages, response, *args, **kwargs):
+        """
+        Stores the messages, returning any unstored messages after trying all
+        backends.
+
+        For each storage backend, any messages not stored are passed on to the
+        next backend.
+        """
+        for storage in self.storages:
+            if messages:
+                messages = storage._store(messages, response,
+                                          remove_oldest=False)
+            # Even if there are no more messages, continue iterating to ensure
+            # storages which contained messages are flushed.
+            elif storage in self._used_storages:
+                storage._store([], response)
+                self._used_storages.remove(storage)
+        return messages