On Tue, Oct 20, 2020 at 2:44 PM Paul Moore <p.f.moore@gmail.com> wrote:
On Tue, 20 Oct 2020 at 13:25, Thomas Wouters <thomas@python.org> wrote:
> On Tue, Oct 20, 2020 at 2:22 PM Paul Moore <p.f.moore@gmail.com> wrote:
>> On Tue, 20 Oct 2020 at 13:13, Thomas Wouters <thomas@python.org> wrote:
>> > The reason for this PEP is that pattern matching will make '_' (but not any other names) have the behaviour suggested in this PEP, but *only* in pattern matching.
>> That's something that should be addressed or debated in the pattern
>> matching PEP. I'm -1 on this PEP being *solely* to patch over a wart
>> in the pattern matching PEP, and the other justifications for the PEP
>> as a standalone proposal don't seem to be convincing people (they
>> don't convince me either, FWIW).
> I did say, in the original email:
> This proposal doesn't necessarily require pattern matching to be accepted -- the new syntax stands well enough on its own -- but I'm recommending this *not* be accepted if pattern matching using the same syntax is not also accepted. The benefit without pattern matching is real but small, and in my opinion it's not worth the added complexity.

Understood. But unless I'm missing something, the pattern matching
PEP(s) is/are in limbo at the moment, there's a lot going on in github
but nothing has been posted here. So I'm not clear what there is to
discuss here at the moment, if the proposal is only relevant if
pattern matching includes it, but no published pattern matching PEP
has suggested it...

They are not in limbo. They are actively being worked on. (At the sprints Brandt mentioned they expect to post updated PEPs later this week.) The Steering Council had a conversation with the PEP authors a while back, discussing various objections and alternatives, including using something else instead of '_'. At that time they were already talking about splitting the PEP up into three parts (which they've since done, but not posted about yet).

I'm not sure how to put it differently than I have in the PEP or the email: I proposed they use ? instead of _ and also apply that to regular unpacking (because it is very easy to see pattern matching as an extension of unpacking assignment), and (besides other disagreements) they were uncomfortable including non-pattern-matching proposals in their PEP. This PEP covers the non-pattern-matching uses of '?'.

(Sorry if the above sounds a little disgruntled, it feels like there's
a lot going in "in private" with the pattern matching PEP and I sort
of feel like a bit more transparency would be good. Maybe I'm

It's not so much 'private' as 'in separate groups', and they're really still processing all the feedback they've received about PEP 622. There's a #pattern-matching channel on the discord server used for the core dev sprints right now (that all sprinters have access to), and the work on PEPs 634, 635 and 636 is happening on the peps repo.

Thomas Wouters <thomas@python.org>

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