Fuzzyman wrote: > Hello all, > > I may well be being dumb (it has happened before), but I'm struggling > to fix some code breakage with Python 2.6. > > I have some code that looks for the '__lt__' method on a class: > > if hasattr(clr, '__lt__'): > > However - in Python 2.6 object has grown a default implementation of > '__lt__', so this test always returns True. > > >>> class X(object): pass > ... > >>> X.__lt__ > <method-wrapper '__lt__' of type object at 0xa15cf0> > >>> X.__lt__ == object.__lt__ > False > > So how do I tell if the X.__lt__ is inherited from object? I can look > in the '__dict__' of the class - but that doesn't tell me if X > inherits '__lt__' from a base class other than object. (Looking inside > the method wrapper repr with a regex is not an acceptable answer...) > > Some things I have tried: > > >>> X.__lt__.__self__ > <class '__main__.X'> > >>> dir(X.__lt__) > ['__call__', '__class__', '__cmp__', '__delattr__', '__doc__', > '__format__', '__getattribute__', '__hash__', '__init__', '__name__', > '__new__', '__objclass__', '__reduce__', '__reduce_ex__', '__repr__', > '__self__', '__setattr__', '__sizeof__', '__str__', > '__subclasshook__'] > >>> X.__lt__.__func__ > Traceback (most recent call last): > File "<stdin>", line 1, in <module> > AttributeError: 'method-wrapper' object has no attribute '__func__' > > > Hmmm... I can get this working with Python 2.6 with: > > if '__lt__' in dir(cls): > > The default implementation of '__lt__' doesn't appear in the dir of > classes. However this fails with Python 3 where the default > implementation *does* appear in the output of 'dir'. Any suggestions? > Methods are objects. How do you know if two references refer to the same object? You use "is":
X.__lt__ is object.__lt__ -- http://mail.python.org/mailman/listinfo/python-list
