python-programs/mro.py at master · chinmayb/python-programs · GitHub

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# Method resolution order

# Old styled class mro
class foo():
    a = "foo"

class bar(foo):
    pass

class baz(foo):
    a = "baz"

class derived(bar, baz):
    pass

instance = derived()
print instance.a


# New styled class
class foo(object):
    a = "foo"

class bar(foo):
    pass

class baz(foo):
    a = "baz"

class derived(bar, baz):
    pass

instance = derived()
print instance.a
print derived.__mro__

# impossible method resolution
class x(object):
    a = "x"

class y(object):
    a = "y"

class v(x, y):
    pass

class w(y, x):
    pass

class A(v, w):
    pass

print A.__mro__