Hello Iap,

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This external method helps a zclass to change the old reference of its base class (an instance of ZClass) to the new one in "new" ZODB.

Thank you very much. I will try it when I will have a little bit of time. (and in particular profit to update to the version of Zope in which you can define DTML-python methods).

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"Zclasses are not robust solutions they mostly seem designed for trivial solutions by largely non programmers."

If we except this BUG and difficulty with DTML Zope to change the inheritance hierarchy, and given that now you can define Python method directly from with the Zope environment, Zope could have been a very good (flexible) environment to design complex applications. I personaly believe that there should exist some way to have very flexible environments to design complex application. Zope has provided us with a very interesting approach (in particular how to combine object orientation and persistance in a system in a very straighforeward way), but not yet enough unfortunatly :-). Thanks again for your suggestion. Thierry Thierry Nabeth Research Fellow, INSEAD CALT (The Centre for Advanced Learning Technologies) http://www.insead.edu/CALT/ PS: I apologize with this mime attachement, but it happens even when I use plain text as a format. I have not found anyway to fix this in Outlook. (Microsoft software !!!).