There has been a problem with zope.interface's verifyObject function that occurs in conjunction with Python properties: when verifyObject checks for the presence of an object's attribute, it does so by using hasattr() which in turn tries a getattr() call. If the attribute is implemented as a property, this may raise an exception which will be masked by hasattr() due to a bare except: clause. One scenario where this is a problem is a property that performs some component lookup which will succeed at application runtime but not in unit tests where verifyObject is commonly used. While it has also been argued that behaviour so complex that it may raise an Exception should not be implemented as a property in the first place, we believe that verifyObject should handle this case better than it currently does. A possible fix would be to add an additional check for a data descriptor on the object's class if the hasattr() test returns False. Are there any objections against modifying verifyObject in this way? Thomas -- Thomas Lotze · tl@gocept.com gocept gmbh & co. kg · forsterstraße 29 · 06112 halle (saale) · germany http://gocept.com · tel +49 345 1229889 0 · fax +49 345 1229889 1 Zope and Plone consulting and development