On 2015-09-09 13:17, Guido van Rossum wrote:
Jukka wrote up a proposal for structural subtyping. It's pretty good. Please discuss.
https://github.com/ambv/typehinting/issues/11#issuecomment-138133867
I'm not totally hip to all the latest typing developments, but I'm not sure I fully understand the benefit of this protocol concept. At the beginning it says that classes have to be explicitly marked to support these protocols. But why is that? Doesn't the existing __subclasshook__ already allow an ABC to use any criteria it likes to determine if a given class is considered a subclass? So couldn't ABCs like the ones we already have inspect the type annotations and decide a class "counts" as an iterable (or whatever) if it defines the right methods with the right type hints? -- Brendan Barnwell "Do not follow where the path may lead. Go, instead, where there is no path, and leave a trail." --author unknown