On 01/26/2015 10:55 AM, Ethan Furman wrote:
> On 01/26/2015 10:40 AM, Paul Moore wrote:
>
>> There *are* some nastily non-intuitive corner cases (for example, if
>> from_env={'a':12} and from_config={'a':13}, I don't have any sort of
>> intuition as to what a would be in f(**from_env, **from_config). I'd
>> go with 12 because the PEP links multiple **-unpackings with
>> collections.ChainMap, but I wouldn't dare rely on that guess).
>
> In the your example
>
> from_env = {'a': 12}
> from_config = {'a': 13}
>
> f(**from_env, **from_config)
>
> I would think 'a' should be 13, as from_config is processed /after/ from_env.
>
> So which is it?Going to the PEP: kwargs = dict(kw_arguments) kwargs.update(more_arguments) function(**kwargs) or, if you know to do so: from collections import ChainMap function(**ChainMap(more_arguments, arguments)) I see the arguments to ChainMap are reversed (more_arguments is first), so in Paul's example 'a' would be 13. -- ~Ethan~
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