[Zodb-checkins] CVS: Zope3/lib/python/Persistence - Module.py:1.25

[Jeremy Hylton]

Update of /cvs-repository/Zope3/lib/python/Persistence
In directory cvs.zope.org:/tmp/cvs-serv7635/Persistence

Modified Files:
	Module.py 
Log Message:
Add some hackery to make sure module registry is not a ghost.

There is a delicate dance going on here between the registry and the
importer.  The registry must be unghostified before the importer tries
to use it, or hard-to-debug failures occur.

We need _p_incref() / _p_decref() methods that guarantee the object
won't be ghostified, but we don't have them yet.



=== Zope3/lib/python/Persistence/Module.py 1.24 => 1.25 ===
--- Zope3/lib/python/Persistence/Module.py:1.24	Thu Oct  3 15:44:23 2002
+++ Zope3/lib/python/Persistence/Module.py	Mon Oct  7 19:29:03 2002
@@ -21,6 +21,7 @@
 import sys
 
 from Persistence import Persistent
+from Persistence.cPersistence import GHOST
 from Persistence.Class import PersistentMetaClass
 from Persistence.Function import PersistentFunction
 from Persistence.IPersistentModuleManager import IPersistentModuleManager
@@ -114,6 +115,7 @@
         self._module._p_changed = True
         moddict = self._module.__dict__
         copy = moddict.copy()
+        self._registry._p_activate() # should lock
         moddict[__persistent_module_registry__] = self._registry
         exec source in moddict
         del moddict[__persistent_module_registry__]
@@ -177,6 +179,23 @@
         return parent
 
 class PersistentModuleImporter:
+    """An import hook that loads persistent modules.
+
+    The importer cooperates with other objects to make sure imports of
+    persistent modules work correctly.  The default importer depends
+    on finding a persistent module registry in the globals passed to
+    __import__().  It looks for the name __persistent_module_registry__.
+    A PersistentModuleManager places its registry in the globals used
+    to exec module source.
+
+    It is important that the registry be activated before it is used
+    to handle imports.  If a ghost registry is used for importing, a
+    circular import occurs.  The second import occurs when the
+    machinery searches for the class of the registry.  It will re-use
+    the registry and fail, because the registry will be marked as
+    changed but not yet have its stated loaded.  XXX There ought to be
+    a way to deal with this.
+    """
 
     def __init__(self):
         self._saved_import = None
@@ -245,8 +264,9 @@
         self.__modules = {}
 
     def findModule(self, name):
+        assert self._p_state != GHOST
         return self.__modules.get(name)
-
+    
     def setModule(self, name, module):
         if name in self.__modules:
             raise ValueError, name