[Zope] monkey patches and persistence

[Brian Lloyd]

Taking a wild guess here, but I'd bet that a user folder is
being modified in a way that doesn't go through one of your
monkey-patched methods, which causes the changes to be lost
if the chain of persistence isn't being maintained.

If it is feasible, I'd say that the best fix would be to
use a PersistentMapping or a BTree instead of a plain dict
to manage your collection of user folders. That should
ensure that the changes are saved without your having to
track / override every method that could possible change
the state of a user or user folder.

hth,


Brian Lloyd        brian at zope.com
V.P. Engineering   540.361.1716
Zope Corporation   http://www.zope.com


> -----Original Message-----
> From: zope-bounces at zope.org [mailto:zope-bounces at zope.org]On Behalf Of
> Dennis Allison
> Sent: Tuesday, December 30, 2003 8:40 PM
> To: zope at zope.org
> Subject: [Zope] monkey patches and persistence
>
>
>
> I have a monkey patch I am using with User Folder (I have multiple
> acl_user instances which are selected dynamically as needed.).  I'm seeing
> some behavior that could be explained by persistence problems.  I'd
> appreciate it if someone would review my approach here to see if I've
> missed something.  Suggestions for a different approach would also be
> appreciated.
>
> I have a Product, "MyUserFolder", which incorporates a number of methods
> which override methods in the Zope UserFolder and/or add new methods.
>
> MyUserFolder consists of a single __init__.py. which includes the
> necessary imports and definitions of the new methods:
>
> 	from AccessControl.User import User
>
> 	def foo( self, param1, param2 ):
> 		....
>
>
> and then patches them in with
>
> 	if 1:
>             from Globals import InitializeClass
>             from AccessControl.User import UserFolder
>
>             # Monkey-patch the original class by
>             # reassigning method references
>
>             UserFolder.foo = foo
>
>         # re-initialize the class
>         InitializeClass( UserFolder )
>
>
> When a compound data structure (e.g., a dictionary of dictionaries) is
> modified in a method, for example, foo, the change is flagged by
> including
> the statement
>
> 	self._p_changed = 1
>
> is incorporated in the method body.
>
> What I observe is the following:
>
> Conceptually, the acl_users structure is replaced with a dictionary of
> acl_users instances, the particular one being selected by a key maintained
> as a session variable.  This works just fine, most of the time.  But,
> occasionally, the acl_users data in one of the instances, just disappears.
> My suspicion is that the date in the acl_users instance is not being
> picked up by the persistence mechanism, but I am at a loss to locate the
> problem.
>
> Comments, help much appreciated.
>
>
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