never use id() with unbound function

gistfile1.txt

$ python2.7 id_anomaly.py 
old_func is not new_func
('old_func:', 41458576, <bound method classobj.member_func of <class __main__.A at 0x278bf58>>)
('new_func:', 41314096, <bound method classobj.member_func of <class __main__.A at 0x278bf58>>)
$ python3.2 id_anomaly.py 
old_func is not new_func
old_func: 140100968595896 <bound method type.member_func of <class '__main__.A'>>
new_func: 140100968596184 <bound method type.member_func of <class '__main__.A'>>

id_anomaly.py

class A:
    @classmethod
    def get_b(cls):
        b = B()
        b.register('func', cls.member_func)
        b.register('func', cls.member_func)
        return b

    @classmethod
    def member_func(cls):
        pass


class B:
    def __init__(self):
        self.func_map = {}

    # From flask.app.add_url_rule
    def register(self, name, new_func):
        old_func = self.func_map.get(name)
        if old_func is not None and old_func is not new_func:
            print("old_func is not new_func")
            print("old_func:", id(old_func), old_func)
            print("new_func:", id(new_func), new_func)
        self.func_map[name] = new_func


A.get_b()