[Python-Dev] Proposal: defaultdict

Phillip J. Eby pje at telecommunity.com
Fri Feb 17 13:52:41 CET 2006

At 10:10 AM 02/17/2006 +0100, Georg Brandl wrote:
>Guido van Rossum wrote:
> >   d = DefaultDict([])
> >
> > can be written as simply
> >
> >   d[key].append(value)
> > Feedback?
>Probably a good idea, has been proposed multiple times on clpy.
>One good thing would be to be able to specify either a default value
>or a factory function.

+1 on factory function, e.g. "DefaultDict(list)".  A default value isn't 
very useful, because for immutable defaults, setdefault() works well 
enough.  If what you want is a copy of some starting object, you can always 
do something like DefaultDict({1:2,3:4}.copy).

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