[Zope] Monkey patching and inheritance

[Dennis Allison]

I am using monkey patches to modify Zope.

I modify UserFolder.py by providing replacements for a number
of methods.  These methods are simply defined in an __init__.py
in a module in the product folder, MyUserFolder.

The UserFolder class is imported, the new overriding methods defined, and,
at the end, InitializeClass is imported from Globals, and the patched
procedure names assigned to their correspondiong  names in Userfolder
namespace, and InitializeClass() called on the UserFolder.

The new code is fairly cautious about persistence.  Use is made of 
PersistentMapping and PersistentList for mutable structures.  

I've been having occasional crashes of the Zope system with a 
diagnostic 

   AttributeError: Surrogate instance has no attribute '_p_oid' 

which I have finally traced to the UserFolder modifications! 
Apparently I have somehow broken the persistence mechanism
in my monkeypatching.

Advise on what the problem might be and how to repair it would be very
helpful.

-dra