init_all_mixin.py

class InitAllMixin(object):
    def __init__(self, *args, **kwargs):
        for base in (c for c in self.__class__.__bases__ if c is not InitAllMixin):
            base_class.__init__(self, *args, **kwargs)

class BaseClassOne(object):
    spam_message = "class_spam"
    def __init__(self):
        self.spam_message = "instance_spam"
        print "init BaseClassOne"
    def do_spam(self):
        print "did {}".format(self.spam_message)

class BaseClassTwo(object):
    def __init__(self):
        print "init BaseClassTwo"


class DerrivedOne(BaseClassTwo, BaseClassOne):
    pass
    
class DerrivedTwo(InitAllMixin, BaseClassTwo, BaseClassOne):
    pass

def main():
    
    objOne = DerrivedOne()
    print '*'*20
    objTwo = DerrivedTwo()
    print '*'*20
    assert(dir(objOne) == dir(objTwo))
    objOne.do_spam()
    print '*'*20
    objTwo.do_spam()
    print '*'*20
    
    return 0

if __name__ == '__main__':
    main()