Thanks for the link, the rationale for rejection seems reasonable.
On Fri, Dec 11, 2020 at 8:19 PM Chris Angelico <ros...@gmail.com> wrote:
> On Sat, Dec 12, 2020 at 11:42 AM Jonathan Crall <erote...@gmail.com>
> wrote:
> >
> > I'm not sure if this has been asked / suggested before.
> >
> > I'm wondering if there is any interest in conditional or loop-based
> `with` statements. I think it could be done without a syntax change.
> >
> > ### Napkin proposal
> >
> > Context managers could define `__if__` or `__for__`, and if those dunder
> methods were defined, then the `with` statement would either behave like a
> conditional or a loop.
> >
> > If `__if__` was defined then
> >
> > ```
> > with Ctx():
> > print('hi')
> > ```
> >
> > would only print `hi` if `__if__` returned True. This doesn't require a
> syntax change.
>
> This part has been proposed before:
> https://www.python.org/dev/peps/pep-0377/
>
>
> > The `__for__` variant would likely need a minor syntax change.
> >
> > ```
> > with item in Ctx():
> > print(item)
> > ```
> >
> > The `__for__` method is a generator that generates arguments of a loop.
> The item will be printed as many times as there are items generated by
> `__for__`.
> >
>
> Not sure that this one has, but it's basically just a context manager
> and a for loop, so I'm not really sure how much you'd gain over just
> using the two constructs independently, given that there'd then be
> massive confusion over "when should I use 'with item in thing' and
> when should I use 'for item in thing'?".
>
> For many use cases, it may be best to write the body as a function,
> which can then be called more than once. You can decorate a function
> in order to do whatever you like, and the return value from the
> decorator could be whatever stats you want to provide (there's no rule
> says that a function decorator has to return a function!).
>
> ChrisA
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--
-Dr. Jon Crall (him)
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