[Python-ideas] Trial balloon: adding variable type declarations in support of PEP 484

[Guido van Rossum]

On Wed, Aug 3, 2016 at 10:29 AM, Paul Moore <p.f.moore at gmail.com> wrote:
> On 3 August 2016 at 17:26, Guido van Rossum <guido at python.org> wrote:
>> But here you're thinking with your runtime hat on
>
> Yep, that's the mistake I was making. Thanks for clarifying.
>
> I've yet to actually use a type checker[1], so I'm still not used to
> thinking in terms of "typecheck-time" behaviour.

That's unfortunate -- the feature I'm developing here is only of
interest to people using a type checker, and the many details of what
it should look like and how it should work will benefit most from
feedback from people who have actually dealt with the existing way of
declaring variables.

> Paul
>
> [1] Off-topic, but I'm not sure if type annotations are powerful
> enough (yet) to track bytes vs str sufficiently to help with resolving
> Python 2 -> Python 3 string handling errors. When I get a chance to
> confirm that's possible, I definitely have some candidate codebases
> I'd like to try my hand with :-)

Not yet, but we're working on it. See
https://github.com/python/typing/issues/208

-- 
--Guido van Rossum (python.org/~guido)