>> That's overly strict. As Raymond shows, it is easy to deal with >> changing method signatures in *cooperative* classes. > I must watch that for sure.
All right, I have read this: https://rhettinger.wordpress.com/2011/05/26/super-considered-super/ There is still something I don't get: how to create cooperative classes when some base classes share some of the parameters? Here is an example modified from Raymond's post: class A: def __init__(self, param1, param2, **kwds): self.param1 = param1 self.param2 = param2 super().__init__(**kwds) class B: def __init__(self, param1, param3, **kwds): self.param1 = param1 self.param3 = param3 super().__init__(**kwds) class X(A,B): def __init__(self, param1, param2, param3, **kwds): print("param1=",param1,"param2=",param2,"param3=",param3) super().__init__(param1=param1,param2=param2,param3=param3,**kwds) print(X.__mro__) x = X(1,2,3) Result: (<class '__main__.X'>, <class '__main__.A'>, <class '__main__.B'>, <class 'object'>) param1= 1 param2= 2 param3= 3 Traceback (most recent call last): File "test.py", line 20, in <module> x = X(1,2,3) File "test.py", line 17, in __init__ super().__init__(param1=param1,param2=param2,param3=param3,**kwds) File "test.py", line 5, in __init__ super().__init__(**kwds) TypeError: __init__() missing 1 required positional argument: 'param1' I could only find this as a solution: class Root: def __init__(self, **kwds): pass class A(Root): def __init__(self, **kwds): self.param1 = kwds['param1'] self.param2 = kwds['param2'] super().__init__(**kwds) class B(Root): def __init__(self, **kwds): self.param1 = kwds['param1'] self.param3 = kwds['param3'] super().__init__(**kwds) class X(A,B): def __init__(self, param1, param2, param3, **kwds): print("param1=",param1,"param2=",param2,"param3=",param3) super().__init__(param1=param1,param2=param2,param3=param3,**kwds) X(1,2,3) But then self documentation and code completion becomes very problematic: http://i.imgur.com/wzlh8uy.png -- https://mail.python.org/mailman/listinfo/python-list
