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From: Vito De Tullio <vito.detullio@gmail.com>
Subject: Re: Safely add a key to a dict only if it does not already exist?
Date: Sat, 19 Jan 2013 09:16:48 +0100
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Xref: csiph.com comp.lang.python:37068

Peter Otten wrote:

>>>> How can I add a key in a thread-safe manner?
>>> I'm not entirely sure, but have you investigated dict.setdefault() ?
>> 
>> but how setdefault makes sense in this context? It's used to set a
>> default value when you try to retrieve an element from the dict, not when
>> you try to set a new one ...
> 
> But it also sets the value if the key is not found:

yeah, sure, but with a fixed value :)

I mean: if the value is not important, why bother at all trying not to 
override it with an if or a lock or other tecniques? doing

    d['key'] = 'fixed_value'

multiple times in different threads is not a problem in my eyes...

-- 
ZeD