How to detect method overloading in subclasses in python?

Question

I have a class that is a super-class to many other classes. I would like to know (in the __init__() of my super-class) if the subclass has overridden a specific method.

I tried to accomplish this with a class method, but the results were wrong:

class Super:    def __init__(self):       if self.method == Super.method:          print 'same'       else:          print 'different'          @classmethod    def method(cls):       pass  class Sub1(Super):    def method(self):       print 'hi'    class Sub2(Super):    pass  Super() # should be same Sub1() # should be different Sub2() # should be same  >>> same >>> different >>> different 

Is there any way for a super-class to know if a sub-class has overridden a method?

Answer 1

You can use your own decorator. But this is a trick and will only work on classes where you control the implementation.

def override(method):   method.is_overridden = True   return method  class Super:    def __init__(self):       if hasattr(self.method, 'is_overridden'):          print 'different'       else:          print 'same'    @classmethod    def method(cls):       pass  class Sub1(Super):    @override    def method(self):       print 'hi'  class Sub2(Super):    pass  Super() # should be same Sub1() # should be different Sub2() # should be same  >>> same >>> different >>> same