[Python-ideas] Inline assignments using "given" clauses

[Guido van Rossum]

I hope Python never has to go there. It's a tooling nightmare.

On Fri, May 4, 2018 at 2:11 PM, Nathaniel Smith <njs at pobox.com> wrote:

> On Fri, May 4, 2018 at 1:53 PM, Tim Peters <tim.peters at gmail.com> wrote:
> > [Tim]
> >>> ...
> >>> It's no longer the case that Python avoided that entirely, since
> >>> "async def", "async for", and "async with" statements were added
> >>> _without_ making "async" a new reserved word.  It may require pain in
> >>> the parser, but it's often doable anyway.  At this stage in Python's
> >>> life, adding new _reserved_ words "should be" an extremely high bar -
> >>> but adding new non-reserved keywords (like "async") should be a much
> >>> lower bar.
> >
> > [Guido]
> >> Do note that this was a temporary solution. In 3.5 we introduced this
> hack.
> >> In 3.6, other uses of `async` and `await` became deprecated (though
> you'd
> >> have to use `python -Wall` to get a warning). In 3.7, it's a syntax
> error.
> >
> > See my "that deserves more thought" at the start, but wrt future cases
> > then ;-)  In 3.5 and 3.6, "everything just works" for everyone.  In
> > 3.7 the implementation gets churned again, to go out of its way to
> > break the handful of code using "async" as an identifier.  It's
> > obvious who that hurts, but who does that really benefit?
> >
> > My experience with Fortran convinces me nobody would _actually_ be
> > confused even if they wrote code like:
> >
> > async def frobnicate(async=True):
> >     if async:
> >         async with ...
>
> IIUC, Javascript has also gone all-in on contextual keywords. The
> realities of browser deployment mean they simply cannot have flag days
> or break old code, ever, meaning that contextual keywords are really
> the only kind they can add at all. So their async/await uses the same
> kind of trick that Python 3.5 did, and I believe they plan to keep it
> that way forever.
>
> FWIW.
>
> -n
>
> --
> Nathaniel J. Smith -- https://vorpus.org
>



-- 
--Guido van Rossum (python.org/~guido)
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