[ZODB-Dev] property broken with/by ZODB?

[Chris Cioffi]

I'm downloading the new version as I write this.  Thanks Tim!

Chris

On Tue, 17 Aug 2004 15:10:24 -0400, Tim Peters <tim at zope.com> wrote:
> [Chris Cioffi]
> > I'm converting a bunch of dicts into proper classes and am having some
> > problems using the property builtin.  When I derive the class from
> > Persistent my properties don't work.  Here's an example:
> >
> > import os.path
> >
> > import ZODB
> > from Persistence import Persistent
> 
> ....
> 
> You didn't say which version of ZODB you're using, but I'm guessing it's
> some flavor of 3.2.  Persistent is a Zope ExtensionClass, and
> ExtensionClasses don't play well with many newer Python class features (such
> as properties).
> 
> So I wouldn't expect this to work in 3.2.i (or 3.1.i, or ...).
> 
> You have a much better chance with ZODB 3.3.  Persistent is a vanilla
> new-style Python class in 3.3, so plays much better with new-style class
> features (like properties).  To run your code under 3.3b2 (the most recent
> 3.3 pre-release), you need to change
> 
>    from Persistence import Persistent
> 
> to
> 
>    from persistent import Persistent
> 
> Then you get the new-style Persistent base class.  There's still an
> ExtensionClass-based version in Zope, but it will no longer ship with ZODB;
> if you try "from Persistence import Persistent" in ZODB 3.3, you get a long
> message, starting with
> 
>    UserWarning: Couldn't import the ExtensionClass-based base class
> 
>    There are two possibilities:
> 
>    1. You don't care about ExtensionClass.  You are importing
>       Persistence because that's what you imported in the past.
>       In this case, you should really use the persistent package
>       instead:
> 
>          >>> from persistent import Persistent
>          >>> from persistent.list import PersistentList
>          >>> from persistent.mapping import PersistentMapping
> 
>    ...
> 
> Anyway, I made that change, and then your program displayed:
> 
>    The Persistent aware obj
>    somefile.txt
>    The "normal" object
>    somefile.txt
> 
> under 3.3b2, which is what I figure you wanted.
> 
> 


-- 
Still searching for an even prime > 2!