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From: Gregory Ewing <greg.ewing@canterbury.ac.nz>
Newsgroups: comp.lang.python
Subject: Re: How to properly override the default factory of defaultdict?
Date: Mon, 15 Feb 2016 21:28:28 +1300
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Herman wrote:
> I want to pass in the key to the default_factory of defaultdict and I found
> that defaultdict somehow can intercept my call to dict.__getitem__(self,
> key),

What's happening here is that defaultdict doesn't actually
override __getitem__ at all. Instead, it overrides __missing__,
which gets called by the standard dict's __getitem__ for a
missing key.

As Steven said, you don't need a defaultdict here at all,
just a dict subclass that defines __missing__ the way you
want.

-- 
Greg