Hello, I would like to mention a very serious bug (for me), that prevent to use inheritance between two classes defined in two different package, if you have to export and reimport those packages. In a previous mail I mentionned a problem of Inheritance lost between packages. I spent a lot of time investigating the problem, and in particular looking in the export file (xml version). First here is the test: Phase 1: create the products and the classes. Create a product PA Create a class A in the product PA. Create a method "test" in class A. (this method display "before"). Create a product PB Create a class B in the product PB which inherits from A. Create an instance a of A. Create an instance b of B. Phase 2: test the inheritance. ==> everything works fine Executing the method "test" on those two instances return. a.test ==> "before" b.test ==> "before" The result is correct. Phase 3: export / reimport product PB, and modify methode "test". Export the product PB. (PB.zexp is generated) Delete the product PB and restart zope. Import the product PB (PB.zexp) and restart zope. Modify the method "test" in class A.. (this method display "after"). Phase 4: test the inheritance. ==> B does not work correctly. Executing the method "test" on those two instances return. a.test ==> "after" b.test ==> "before" ####### this is incorect. !!!!!! I spent a lot of time investing this problem, in particular looking in the xml export file. The problem is that when you export PB, the exported file also contain the definition of class A. When you re-import PB, B inherits from a class A that is different from the class A that is in the product PA. You have a kind of Zombie class A. (note: reimporting class A doesn't solve the problem). If someone has some idea how to fix this bug which almost forbid the use of inheritance between products in zope (unless you have a master server that never import anything) ?! Thierry Nabeth Research Fellow, INSEAD CALT (The Centre for Advanced Learning Technologies) http://www.insead.edu/CALT/ Thierry.Nabeth@insead.fr