[Tutor] quirky multiple inheritance example!?

[Kent Johnson]

Alan Gauld wrote:
>>> The problem is that super appears to only work with single inheritance.
> 
> 
>> That's ironic - super() is intended to ease some of the problems with 
>> multiple inheritance especially diamond patterns. Some docs are here:
>> http://www.python.org/2.2.3/descrintro.html#cooperation
>>
>> The problem with the OP is that not all the classes involved use super().
> 
> I tried that. Before posting I went back and reread the super docs and
> tried building an MI lattice but, whatever I did, super only ever called 
> the
> first listed superclass. If it had a super it called its superclass but the
> second superclasss never got initialised so far as I could tell!

Works for me. Each class must call super(...).__init__(). The first arg 
to super() must be the class in which the call appears. One mistake is 
to call super(self.__class__, self) - this is not correct. Here is an 
example:

  >>> class A(object):
  ...   def __init__(self):
  ...     print 'A.__init__()'
  ...     super(A, self).__init__()
  ...
  >>> class B(object):
  ...   def __init__(self):
  ...     print 'B.__init__()'
  ...     super(B, self).__init__()
  ...
  >>> class C(A, B):
  ...   def __init__(self):
  ...     print 'C.__init__()'
  ...     super(C, self).__init__()
  ...
  >>> C()
C.__init__()
A.__init__()
B.__init__()
<__main__.C object at 0x00A32BB0>

Kent