Has comparison of instancemethods changed between python 2.5 and 2.4?

[Frank Niessink]

Hi,

I'm trying to get an application working with Python 2.5 that works fine 
with Python 2.4. This issue occurs both on Windows XP as well as on Mac OSX.

Some context: I use the publisher/subscribe pattern. Observers can 
register a callback with a central 'Publisher' like this:

def registerObserver(self, observer, eventType):
     ''' Register an observer for an event type. The observer is a
         callback method that should expect one argument, an instance
         of class Event defined above.
         The eventType can be anything hashable, typically a string. '''
     observerList = self.__observers.setdefault(eventType, [])
     if observer not in observerList:
         observerList.append(observer)


Now, with Python 2.5 (and not with Python 2.4) I have a callback that is 
not being added to the list because, apparently, it compares equal to 
some of the callbacks already in the list. However, the instance the two 
methods belong to are different, i.e. id(callback) returns different 
values for the two methods. Both callbacks are of type <type 
'instancemethod'>. Further investigation shows that "observer == 
observerList[1]" is True.

Has instancemethod.__cmp__ changed between python 2.4 and 2.5?

Thanks, Frank