On 5 September 2016 at 20:15, Guido van Rossum <gu...@python.org> wrote:
> There are actually at least two separate cases: if x is a local > variable, the intention of `x: <type>` is quite different from when x > occurs in a class. > If I understand you correctly this also matches my mental model. In local scope x: ann = value acts like a filter allowing only something compatible to be assigned at this point (and/or casting to a more precise type). While in class or module it is a part of an "API specification" for that class/module. > I am at a loss how to modify the PEP to avoid this misunderstanding, > since it appears it is entirely in the reader's mind. The PEP is not a > tutorial but a spec for the implementation, ... > I was thinking about changing terminology to name annotations, but that will not solve problem. The PEP mentions a separate document (guidelines) that will be published. I think a real solution will be to make a separate PEP that will explain in details what is preferred meaning of types and what people and machines could do with types. Is anyone interested in going in this direction? I would like to especially invite Mark, you have a lot of experience with types inference that would be very helpful (also it seems to me that you are concerned about this). -- Ivan
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