Support serialization of objects that return a single string from __r…

…educe__().

This allows us to serialize module globals, especially interfacaes and
classes.

CHANGES.txt

@@ -5,6 +5,9 @@ CHANGES
 0.9.0 (unreleased)
 ------------------
 
+- Feature: Support serialization of objects that return a single string from
+  ``__reduce__()``.
+
 - Feature: Added a container-level cache to the ``MongoContainer``
   object. This cache is only used within the transaction, but it reduced calls
   to Mongo by 40% in a real world use. The cache can be turned off by setting
@@ -49,7 +52,6 @@ CHANGES
   flushed.
 
 
-
 0.8.4 (2013-06-13)
 ------------------
 

src/mongopersist/serialize.py

@@ -152,6 +152,10 @@ def get_non_persistent_state(self, obj, seen):
         reduced = obj.__reduce__()
         # The full object state (item 3) seems to be optional, so let's make
         # sure we handle that case gracefully.
+        if isinstance(reduced, str):
+            # When the reduced state is just a string it represents a name in
+            # a module. The module will be extrated from __module__.
+            return {'_py_constant': obj.__module__+'.'+reduced[0]}
         if len(reduced) == 2:
             factory, args = reduced
             obj_state = {}
@@ -462,6 +466,8 @@ def resolve(self, dbref):
             return klass
 
     def get_non_persistent_object(self, state, obj):
+        if '_py_constant' in state:
+            return self.simple_resolve(state.pop('_py_constant'))
         if '_py_type' in state:
             # Handle the simplified case.
             klass = self.simple_resolve(state.pop('_py_type'))