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[Python-Dev] PEP 484 proposal: don't default to Optional if argument default is None

Guido van Rossum guido at python.org
Tue May 9 23:31:52 EDT 2017 
On Tue, May 9, 2017 at 7:37 PM, Nick Coghlan <ncoghlan at gmail.com> wrote:

> On 10 May 2017 at 08:51, Brett Cannon <brett at python.org> wrote:
> > On Tue, 9 May 2017 at 11:11 Carl Meyer <carl at oddbird.net> wrote:
> >> It might be nice to have a less verbose syntax for Optional, but that
> >> can be a separate discussion.
> >
> > You should be able to do that today with `from typing import Optional as
> Eh`
> > or whatever your preferred optional/maybe name is. :)
>
> While "from typing import Optional as Opt" can indeed help, perhaps
> PEP 505 should be updated to discuss this point in addition to the
> current proposals for None-aware binary operators?
>
> If it included a ? prefix operator as a shorthand for
> "typing.Optional[<expr>]", that would shorten affected declarations
> back to:
>
>     def handle_employee(e: ?Employee = None) -> None: ...
>

I really don't want to go there. And this idea should definitely not be a
condition for removing the existing PEP 484 feature. Whatever gets done
syntax-wise won't affect anyone who needs any kind of backward
compatibility anyways, and that's very important for practical adoption of
PEP 484.

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