On Thu, 2008-11-06 at 11:20 +0200, Marius Gedminas wrote: > On Wed, Nov 05, 2008 at 03:59:07PM +0100, Christian Theune wrote: > > On Wed, 2008-11-05 at 16:00 +0200, Marius Gedminas wrote: > > > On Wed, Nov 05, 2008 at 11:48:35AM +0100, Christian Theune wrote: > > > > On Wed, 2008-11-05 at 11:31 +0100, Laurence Rowe wrote: > > > > > Broken objects occur when the class for a pickled object cannot be > > > > > imported. To change the location of a class, you need to provide an > > > > > alias at the old location so that the object can be unpickled, i.e. > > > > > MyOldClassName = MyNewClassName. You can only remove MyOldClassName > > > > > after you have updated all of the pickles (with your code below). > > > > > > > > Note: We made a relatively good experience by removing those symbols > > > > from their original modules and provide a generation which first sets up > > > > dummies, then runs migration code to remove/rebase those objects and > > > > then remove the dummies again. > > > > > > How do you do that? Monkey-patching? > > > > Yes. Monkey-patching *and* monkey-unpatching. > > Thought so. > > By the way, this has a potential failure mode when you need to evolve > more than one generation, and a previous generation script needs to > access those objects in the old location before your new generation > script sets up the dummies.
Yes. Our deployments are under relatively tight control and we check that generations work on a copy of a database before doing the actual roll-out. In this case we currently estimate that we'll need to change that earlier generation. Generations assume that the code looks like what it did when the generation was written -- which certainly doesn't hold. Christian -- Christian Theune · [EMAIL PROTECTED] gocept gmbh & co. kg · forsterstraße 29 · 06112 halle (saale) · germany http://gocept.com · tel +49 345 1229889 7 · fax +49 345 1229889 1 Zope and Plone consulting and development
Description: This is a digitally signed message part
_______________________________________________ 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