Could you summarize your proposal in a few lines? I've tried to read that email several times now and I still don't follow the proposal. You can leave the reasoning *why* you believe your proposal is better out -- I just want to see what it will look like (how to define a type guard, and how to use it).
On Tue, Feb 16, 2021 at 11:39 AM Joseph Perez <jope...@hotmail.fr> wrote: > I've proposed PEP 593 `Annotated` too, but in the typing-sig mailing list: > https://mail.python.org/archives/list/typing-...@python.org/message/CVLLRWU7MU7T2AMC4P7ZEG4IMJF6V5UL/ > and Guido had the following answer: > > I see PEP 593 as a verbose solution to the problem "how do we use > annotations for static typing and for runtime metadata simultaneously". > Type guards solve a problem that's entirely in the realm of static typing, > so IMO it would be an abuse of Annotated. > > (I've also written in the mail about checked cast as an alternative > solution to type guard.) > > > For the most extensible approach both -> TypeGuard(...) and > -> Annotated[bool, TypeGuard(...)] could be allowed, which would open the > path for future non-type-annotations, which could be used regardless of > whether the code > is type-annotated. > I've proposed a possible implementation in my mail linked above. > _______________________________________________ > 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/B3QZTPW6S6LHQKX476VRYAWEVMZ26VHH/ > 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/>
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