On Fri., 13 Nov. 2020, 4:01 am Guido van Rossum, <gu...@python.org> wrote:
> The position of PEP 622/634/535/636 authors is clear: we see this as a > necessary feature to support using enums (e.g. Color.RED) or constants > defined in other modules (e.g. re.I) when simple switch functionality is > being migrated from literals (e.g. case 404) to named constants (e.g. case > HTTPStatus.NOT_FOUND). Bothering users with the technicality of needing to > use '==' here is a big usability hit. > Right, this was a part of Steven D'Aprano's counterproposal that I found compelling, so PEP 642 now keeps the inferred equality constraints for the patterns that are unambiguous in context. The "==" is only required when the expression would otherwise be interpreted as a capture pattern, or wouldn't be allowed in a pattern at all. Cheers, Nick. > On Thu, Nov 12, 2020 at 7:38 AM Baptiste Carvello < > devel2...@baptiste-carvello.net> wrote: > >> Hi, >> >> Le 08/11/2020 à 07:47, Nick Coghlan a écrit : >> > Hi folks, >> > >> > I have updated PEP 642 significantly based on the feedback received >> > over the past week. >> > >> > [...] >> a change that I feel is insufficiently discussed is the choice to have >> "attr_constraint" as an inferred constraint. I can think of arguments to >> defer it for now at least: >> >> * it is a one way door (if dotted names are made a constraint pattern >> now, they can't become a capture pattern later); >> >> * it makes a difference from assignment target syntax, where you can >> assign to a dotted name; >> >> * the shorthand notation is less valuable than for literals, as dotted >> names are verbose already, 3 more characters make little difference; >> >> * the user has no explicit syntax to override the inferred semantics. >> >> I feel like some discussion of this choice in the PEP would make sense. >> >> Cheers, >> Baptiste >> _______________________________________________ >> Python-Dev mailing list -- python-dev@python.org >> To unsubscribe send an email to python-dev-le...@python.org >> https://mail.python.org/mailman3/lists/python-dev.python.org/ >> Message archived at >> https://mail.python.org/archives/list/python-dev@python.org/message/RQPUV7PABLBNYJ7FI7QYCS6TKJ4H2Q2A/ >> Code of Conduct: http://python.org/psf/codeofconduct/ >> > > > -- > --Guido van Rossum (python.org/~guido) > *Pronouns: he/him **(why is my pronoun here?)* > <http://feministing.com/2015/02/03/how-using-they-as-a-singular-pronoun-can-change-the-world/> > _______________________________________________ > Python-Dev mailing list -- python-dev@python.org > To unsubscribe send an email to python-dev-le...@python.org > https://mail.python.org/mailman3/lists/python-dev.python.org/ > Message archived at > https://mail.python.org/archives/list/python-dev@python.org/message/DPDHLPKAG3ATDH47NZNWGPK2FKBCY7WR/ > Code of Conduct: http://python.org/psf/codeofconduct/ >
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