Has comparison of instancemethods changed between python 2.5 and 2.4?

[Ziga Seilnacht]

Frank Niessink wrote:
> I tried to lookup the python source code where the actual comparison
> happens. I think it is in methodobject.c (I'm not familiar with the
> python source so please correct me if I'm wrong), meth_compare. That
> function did not change between python 2.4.4 and 2.5. Moreover, the
> implementation suggests that the only way for two methods to be equal is
> that their instances point to the same object and their method
> definitions are the same. Am I interpreting that correctly?

No, the comparison happens in function instancemethod_compare in file
classobject.c:
http://svn.python.org/view/python/trunk/Objects/classobject.c?view=markup

This method was changed in Python 2.5. Previously, two instancemethods
compared equal if their im_self attributes were *identical* and their
im_func attributes were equal. Now, they compare equal if their im_self
attributes are *equal* and their im_func attributes are equal. See this
change:
http://svn.python.org/view?rev=46739&view=rev

A small example:

>type cmpmethod.py

class Test(object):

    def meth(self):
        pass

    def __eq__(self, other):
        return True

>python24
Python 2.4.4 (#71, Oct 18 2006, 08:34:43) ...
>>> from cmpmethod import Test
>>> a, b = Test(), Test()
>>> a.meth == b.meth
False
>>> ^Z

>python25
Python 2.5 (r25:51908, Sep 19 2006, 09:52:17) ...
>>> from cmpmethod import Test
>>> a, b = Test(), Test()
>>> a.meth == b.meth
True
>>> ^Z

If you think this is a bug, you should report it to the bugtracker:
http://sourceforge.net/bugs/?group_id=5470

Ziga