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[Python-Dev] Arbitrary non-identifier string keys when using **kwargs

Brett Cannon brett at python.org
Fri Oct 5 17:50:30 EDT 2018 
I'm also fine with saying that keys in **kwargs that are not proper
identifiers is an implementation detail.

On Thu, 4 Oct 2018 at 02:20, Serhiy Storchaka <storchaka at gmail.com> wrote:

> 04.10.18 11:56, Steven D'Aprano пише:
> > While keyword arguments have to be identifiers, using **kwargs allows
> > arbitrary strings which aren't identifiers:
> >
> > py> def spam(**kwargs):
> > ....     print(kwargs)
> > ....
> > py> spam(**{"something arbitrary": 1, '\n': 2})
> > {'something arbitrary': 1, '\n': 2}
> >
> >
> > There is some discussion on Python-Ideas on whether or not that
> > behaviour ought to be considered a language feature, an accident of
> > implementation, or a bug.
> >
> > Can we get some guidence on this please?
>
> This is an implementation detail. Currently CPython doesn't ensure that
> keyword argument names are identifiers for performance reasons. But this
> can be changed in future versions or in other implementations.
>
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