Lazy Crazy Coder's blog

Multiple inheritance in the Python and «diamond problem»

Published at 27, August 2008, author art. Tags: python

Hello, all!

Today I've write small and simple test for multiple inheritance in the python:

#!/usr/bin/env python
class Base(object):
    def say(self, indent = 0):
        print '%s%s' % ('\t'*indent, 'Base')
class ChildA(Base):
    def say(self, indent = 0):
        print '%s%s' % ('\t'*indent, 'ChildA')
        super(ChildA, self).say(indent+1)
class ChildB(Base):
    def say(self, indent = 0):
        print '%s%s' % ('\t'*indent, 'ChildB')
        super(ChildB, self).say(indent+1)
class ChildC(ChildA, ChildB):
    def say(self, indent = 0):
        print '%s%s' % ('\t'*indent, 'ChildC')
        super(ChildC, self).say(indent+1)
obj = ChildC()
obj.say()

Here is the output of the program:

ChildC
    ChildA
        ChildB
            Base

As you can see, methods are evaluated in right order!

See more information about multiple inheritance in the official Python Tutorial.

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