Jim Fulton wrote at 2008-1-7 16:04 -0500: >... >> If "__implements__" is inherited, why is "__provides__" not >> inherited? > >__provides__ (in this context) is a class attribute. I don't support >(and don't want to support) inheritance between class objects.
Where can I read about the "__provides__" semantics? Where is it documented? Python does support class attribute inheritance as can be seen by this small transscript: >>> class C(object): x=1 # class attribute "x" ... >>> class CD(C): pass ... >>> CD.x # class attribute "x" inherited by "CD" 1 Why do you think that "zope.interface" should not support class attribute inheritance. > .... >> This fails for classes magically stuffed with a "__provides__" >> descriptor. > >It also fails for any descriptor that sometimes raises attribute >errors. Someone should report this as an inspect bug. This would be >so easy to fix. True -- but if they are not far more ready to admit a bug, there is little chance that this gets fixed. > .... >I suggest monkey-fixing inspect.getmembers. This is a small function >that should be easy to replace with a non-broken version. This is already done. "dm.reuse" allows in many cases to fix functions without code duplication. Nevertheless, I am convinced to face a bug both in "zope.interface" as well as in "inspect". > .... >>> My main gripe with the way this works is that classes get mutated. >>> If >>> I ever redo this someday, I'd use a data structure external to the >>> classes. Modifying the classes was a mistake. >> >> Yes. That, too, would have avoided the bug. > > >Yes, it would have avoided the inspect bug. IMO, it would also have >been cleaner. If someone wants to volunteer to change it, I'll try to >provide some oversight. Unfortunately, it's not a small task, which is >why I'm not volunteering to do it. You probably have already a notion about the semantics of "__provides__". If someone else should change anything with it, he will need a precise understanding what "__provides__" means, which properties is has and which not. Moreover, backward compatibility needs to be taken into account. When "__provides__" stops to be an ill behaving class attribute, then this obviously is a change in behavior. -- Dieter _______________________________________________ Zope-Dev maillist - Zope-Dev@zope.org http://mail.zope.org/mailman/listinfo/zope-dev ** No cross posts or HTML encoding! ** (Related lists - http://mail.zope.org/mailman/listinfo/zope-announce http://mail.zope.org/mailman/listinfo/zope )