default behavior

[Christian Heimes]

> The truth, as Christian says above and as Raymond Hettinger recently 
> pointed out [1], is that __missing__ is used to *define* defaultdict as 
> a subclass of dict -- it's not used *by* defaultdict.

Your answer is confusing even me. ;)

Let me try an easier to understand explanation. defaultdict *implements*
__missing__() to provide the default dict behavior. You don't have to
subclass from defaultdict to get the __missing__() feature. It's part of
the dict interface since Python 2.5.

Christian