* Shane Hathaway <shane@hathawaymix.org> [2009-12-03 11:44]:
Wolfgang Schnerring wrote:
The minimal reproduction recipe to see the error is this:
class Slotted(object): __slots__ = ('__provides__')
zope.component.provideAdapter( lambda x: True, (Slotted,), zope.interface.Interface)
Which will raise File "/home/wosc/.python-eggs/zope.component-3.7.1-py2.6.egg/zope/component/registry.py", line 419, in _getAdapterRequired elif not ISpecification.providedBy(r): TypeError: 'member_descriptor' object is not callable
It looks to me like a possible bug in zope.interface. Try deleting _zope_interface_coptimizations.so to hopefully expand that traceback.
Thanks for the hint! This enabled me to step through all of it with pdb, which turns up zope/interface/declarations.py:1249 def getObjectSpecification(ob): provides = getattr(ob, '__provides__', None) if provides is not None: return provides [...] So it seems that __provides__ is part of the zope.interface mechanics, and if unset that attribute should not exist -- but when using __slots__ it always exists, namely as a 'member_descriptor' object. I'll try and see whether I can come up with a way for zope.interface to do the Right Thing(tm) in this situation. Wolfgang