"""

There is a way to put keys of any type in a type's dictionary.

I think this allows various kinds of crashes, but so far I have only

found a convoluted attack of _PyType_Lookup(), which uses the mro of the

type without holding a strong reference to it.  Probably works with

super.__getattribute__() too, which uses the same kind of code.

"""

class MyKey(object):

    def __hash__(self):

        return hash('mykey')

    def __cmp__(self, other):

        # the following line decrefs the previous X.__mro__

        X.__bases__ = (Base2,)

        # trash all tuples of length 3, to make sure that the items of

        # the previous X.__mro__ are really garbage

        z = []

        for i in range(1000):

            z.append((i, None, None))

        return -1

class Base(object):

    mykey = 'from Base'

class Base2(object):

    mykey = 'from Base2'

# you can't add a non-string key to X.__dict__, but it can be

# there from the beginning :-)

X = type('X', (Base,), {MyKey(): 5})

print X.mykey

# I get a segfault, or a slightly wrong assertion error in a debug build.