(Adding zodb-dev@zope.org back to Cc:) On Thu, Jul 03, 2008 at 09:14:27AM -0400, Erik Dahl wrote: > On Jul 2, 2008, at 10:55 AM, Marius Gedminas wrote: > > >> > >>inst.__class__ = NewClass > > > >Is inst a persistent object? Then your only chance to get this to > >work > >is to find *all* objects that reference inst and mark them _p_changed. > > Yes inst is a persistent object. Hum ok I will give this a try. > > > > >>The class is also stored in every reference to that object. > > Well that something new to me... how come? Seems like they only need > the oid.
My guess is that's for performance reasons. When you load the state of
an object X with an attribute 'y' referring to object Y, you end up with
two objects in memory: X with all of its state, and Y which is a "ghost"
(it only knows its own class and oid). To create the ghost you need to
know its class. To avoid loading the pickle of Y when you only need X,
every reference to Y stores both its oid and its class.
If you look at ZODB/serialize.py and look at ObjectWriter.persistent_id,
you'll see it stores references to persistent objects as (oid, class)
tuples.
Marius Gedminas
--
> find /lib/modules/2.4.17-expt/kernel/ -type f|while read i; do insmod $i; done
You're sick. I like you.
-- Andrew Morton on lkml
signature.asc
Description: Digital signature
_______________________________________________ For more information about ZODB, see the ZODB Wiki: http://www.zope.org/Wikis/ZODB/ ZODB-Dev mailing list - ZODB-Dev@zope.org http://mail.zope.org/mailman/listinfo/zodb-dev
