[Zope] Persistence.py does not define Persistent

[Dieter Maurer]

Skip Montanaro writes:
 > 
 > I'm trying to publish my own module with ZServer (from Zope 2.2.0).  I get
 > the following traceback:
 > 
 >     ....
 > 	from Persistence import Persistent
 >     ImportError: cannot import name Persistent
 > 
 > When I look at lib/python/Persistence.py, all I see is a copyright notice
 > and the following short doc string:
 > 
 >     """Provide access to Persistent and PersistentMapping
 > 
 >     This avoids dependency on the database package name.
 >     """
 > 
 > I can't find a definition of an object named Persistent (probably ought to
 > be a class or ExtensionClass, based upon the usage I saw) anywhere in the
 > Zope 2.2.0 tree.

"Persistence" is only a "placeholder" module that gets filled
by the really used Object Database package (ZODB, BoboPOS2, BoboPOS3, ...)
that implements persistence.

For the current Zope, "ZODB/__init__.py" fills this module
with "cPersistence.Persistent" and "PersistentMapping".


By the way, Andrew Kuchling works on separate packages for
various Zope parts. I think, ZODB is one of this packages.
There was an announcement in zope-dev.


Dieter