I needed to dynamically generate local roles for an Archetypes based content object today. Different layers in my Plone stack breaks all rules and reads the __ac_local_roles__ variable directly, instead of calling get_local_roles() So to maximize the compatibility between Zopes zmi and Plones local roles management I wanted to make '__ac_local_roles__' a property with setters and getters. My AT class was based via a few hops on: 'from ExtensionClass import Base'. And as far as I understand from the release notes Zope 2.8.x should use extension classes based on new style classes. So the property function should work. This code below works in plain Python. But when I add them to my zope class, and run the tester() method I get an "Attributer Error: __ac_local_roles__" Any ideas/comments? # -*- coding: latin-1 -*- class PropTest: def get__ac_local_roles__(self): return self.__mxm__ac_local_roles__ def set__ac_local_roles__(self, value): self.__mxm__ac_local_roles__ = value def del__ac_local_roles__(self): del self.__mxm__ac_local_roles__ __ac_local_roles__ = property(get__ac_local_roles__, set__ac_local_roles__, del__ac_local_roles__, "Local roles on object") def tester(self): return self.__ac_local_roles__ if __name__ == '__main__': p = PropTest() p.__ac_local_roles__ = 'working' print p.tester() -- hilsen/regards Max M, Denmark http://www.mxm.dk/ IT's Mad Science Phone: +45 66 11 84 94 Mobile: +45 29 93 42 96