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From: Thomas Jollans on 2 Jul 2010 05:32
On 07/02/2010 11:26 AM, Chris Rebert wrote:
> On Fri, Jul 2, 2010 at 2:20 AM, Thomas Jollans <thomas(a)jollans.com> wrote:
>> On 07/02/2010 06:11 AM, Steven D'Aprano wrote:
>>> I would like to better understand some of the design choices made in
>>> collections.defaultdict.
> <snip>
>>> Second, why is the factory function not called with key? There are three
>>> obvious kinds of "default values" a dict might want, in order of more-to-
>>> less general:
>>>
>>> (1) The default value depends on the key in some way: return factory(key)
>>
>> I agree, this is a strange choice. However, nothing's stopping you from
>> being a bit verbose about what you want and just doing it:
>>
>> class mydict(defaultdict):
>> def __missing__(self, key):
>> # ...
>>
>> the __missing__ method is really the more useful bit the defaultdict
>> class adds, by the looks of it.
>
> Nitpick: You only need to subclass dict, not defaultdict, to use
> __missing__(). See the part of the docs Raymond Hettinger quoted.
>

Sorry Raymond, I didn't see you.

This is where I cancel my "filter out google groups users" experiment.
From: Steven D'Aprano on 2 Jul 2010 19:59
On Fri, 02 Jul 2010 04:11:49 +0000, Steven D'Aprano wrote:

> I would like to better understand some of the design choices made in
> collections.defaultdict.
[...]


Thanks to all who replied.


--
Steven


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