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

[Jeff Hardy]

On Sun, Oct 14, 2018 at 12:15 PM Jeff Allen <ja.py at farowl.co.uk> wrote:
>
>
> On 10/10/2018 00:06, Steven D'Aprano wrote:
>
> On Tue, Oct 09, 2018 at 09:37:48AM -0700, Jeff Hardy wrote:
>
> ...
>
> From an alternative implementation point of view, CPython's behaviour
> *is* the spec. Practicality beats purity and all that.
>
> Are you speaking on behalf of all authors of alternate implementations,
> or even of some of them?
>
> It certainly is not true that CPython's behaviour "is" the spec. PyPy
> keeps a list of CPython behaviour they don't match, either because they
> choose not to for other reasons, or because they believe that the
> CPython behaviour is buggy. I daresay IronPython and Jython have
> similar.
>
> While agreeing with the principle, unless it is one of the fundamental differences (GC, GIL), Jython usually lets practicality beat purity. When faced with a certain combination of objects, one has to do something, and it is least surprising to do what CPython does. It's also easier than keeping a record.

This is how it is for IronPython as well. When the pool of potential
users is already small, one cannot afford to get too pedantic about
whether something is in the spec or not. Matching what CPython does is
the easiest way to make sure as many people as possible can use an
alternative implementation.

- Jeff