[Zope] Checking object's class

Hi, I use custom Zope products written in Python. In several cases, I have to check for published object's class and adapt several front-end parameters according to it. My questions are simple : - is it better to test for "object.meta_type" or "isinstance (object, class)" (concerning performances as well as the possibility to create subclasses) ? - as long as subclasses are not to be created from ZMI but from another backoffice, is it possible to use the same "meta_type" for a class and all it's subclasses ? Thanks, Thierry -- Linux every day, keeps Dr Watson away... http://gpc.sourceforge.net -- http://www.ulthar.net