Python 2.6: Determining if a method is inherited

[Aaron "Castironpi" Brady]

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...)

They're of different types.  I'm not sure how much you could use that, 
or how reliable it is.

 >>> class A( object ):
...     pass
...
 >>> class B( object ):
...     def __lt__( self, other ):
...             pass
...
 >>> hasattr( A, '__lt__' )
True
 >>> hasattr( B, '__lt__' )
True
 >>> A.__lt__
<method-wrapper '__lt__' of type object at 0x00B81D48>
 >>> B.__lt__
<unbound method B.__lt__>
 >>>