[Python-3000] Type parameterization (was: Re: Type annotations: annotating generators)

[Jim Jewett]

On 5/19/06, Collin Winter <collinw at gmail.com> wrote:
> ... what do you think of ... having bracket-based parameterization be
> redirected a call to some double-underscore method

It already is -- to __getitem__.

Having it go to something else just because you're in a function
definition is asking for trouble.  What should happen in the following
case?

    b=dict(strict=check1, lenient=check2, normal=check3)

    def foo(a:b["normal"]): pass

Should it really look for some special method on b (or b's type) just
because it is in a signature context?  Today, the annotation
expression would evaluate to check2, and I'm not looking forward to
figuring out all the corner cases on when that wouldn't happen.

-jJ