On Sat, 13 Feb 2021 at 17:33, Guido van Rossum <gu...@python.org> wrote: > On Sat, Feb 13, 2021 at 2:38 AM Paul Moore <p.f.mo...@gmail.com> wrote: >> >> I have to agree here. I'm not a frequent user of type hints yet, but I >> am starting to have to maintain code that has type hints, and from a >> maintenance perspective, I have to say that this would be really hard >> to deal with. If I saw this for the first time "in the wild", I'd have >> no idea what to do with it. > > > Think of it as new syntax. Of course you have to learn it (or Google it). Is > it easy to learn? I think so. Is it easy to recognize once you've seen and > understood it once? Yes. Is it easy to use it correctly given an example? > Yes again.
But looking at it, it's *not* new syntax, it's a return type of TypeGuard[List[str]], which is perfectly good syntax today. I can look up what the type TypeGuard is, but most of the time, when maintaining code, I don't do that - I just think "hmm, returns Foo, that's all I need to know right now". But then I discover that it's returning a boolean, and I'm confused. And it's always going to be an exception to the rule that what's after the -> is the type of the return value. I personally think "Special cases aren't special enough to break the rules" applies here, but I admit I don't know how special this case is, nor do I know why no less exceptional alternative is possible. Of course I can look it up, but it's a distraction from what I was trying to do. Of course it's easy to google, but it's the *only* annotation I've ever needed to google. Of course it's optional and only affects type checkers, but I don't control everything that gets added to code bases I support. *shrug* it makes little difference in the grand scheme of things, it'll go in if enough people who have influence over the decision are OK with it. And I'm sure it fills a need for certain types of project. It's not going to make my life impossible either way. But if impressions from casual users are being counted, I remain -1. Paul _______________________________________________ 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/P6SZAUSQFLSOGMUDXYKD3MGGWZSJ7LYW/ Code of Conduct: http://python.org/psf/codeofconduct/
