Re: How to properly override the default factory of defaultdict?

From	Gregory Ewing <greg.ewing@canterbury.ac.nz>
Newsgroups	comp.lang.python
Subject	Re: How to properly override the default factory of defaultdict?
Date	2016-02-15 21:28 +1300
Message-ID	<didgheFteu2U1@mid.individual.net> (permalink)
References	<mailman.122.1455495511.22075.python-list@python.org>

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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

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How to properly override the default factory of defaultdict? Herman <sorsorday@gmail.com> - 2016-02-14 16:17 -0800
  Re: How to properly override the default factory of defaultdict? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2016-02-15 14:56 +1100
  Re: How to properly override the default factory of defaultdict? Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2016-02-15 21:28 +1300

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