Stefan Franke wrote:

[Pleased of having caught Jim Fulton in verbose mode 8-]

...

You can store any complex Python data in the DB subject to: [...] - Subobjects of persistent objects must be "persistent" or they must be immutable, or be used immutably, as in:

So class Persistent's __setattr__ is basically also the level that transaction and undo support work on?

I'm not sure what you mean by this. Transaction boundaries are detemined by transaction calls, which are normally made by ZPublisher. Peristent's __setattr__ takes care of registering object changes. Now that you mention it, there is another restriction on persistent objects, they should not implement custom __setattr__ or __getattr__ methods.

Can I expect the undo support to work if I take care of the persistence rules, regardless of cyclic and acyclic structures?

Yes.

Propably about time to switch to Zope-dev...

OK, done. :) Jim -- Jim Fulton mailto:jim@digicool.com Python Powered! Technical Director (888) 344-4332 http://www.python.org Digital Creations http://www.digicool.com http://www.zope.org Under US Code Title 47, Sec.227(b)(1)(C), Sec.227(a)(2)(B) This email address may not be added to any commercial mail list with out my permission. Violation of my privacy with advertising or SPAM will result in a suit for a MINIMUM of $500 damages/incident, $1500 for repeats.