On Thu, Sep 22, 2016 at 11:42 AM, Steven D'Aprano <steve@pearwood.info> wrote:

> This makes it necessary to use string representation for names
> that are not yet bound, which affects almost every class definition.

Almost every class? Really? I find that implausible. Still, I can see it
affecting *many* class definitions, so let's not quibble.

I would say this affects a "rare class here and there." Almost all typing will be with things defined in the `typing` module (or built-ins). I guess once in a while we'll see e.g. `Sequence[CustomThing]`, but it will be uncommon for that typing involving `CutomThing` to be within CustomThing itself (well, unless you use much more recursion than Python encourages).

-1 on complicating the simple Python model that expressions are
evaluated when they are reached.

I think there is a decent argument for a more general concept of macros, or symbols, or simpler delayed evaluation than lambda for Python in general. I see places where this would be very nice for Pandas, for example, and for Dask (I work with the developers of both of those projects).

In such a hypothetical future world we might come to allow, e.g. `Sequence[#CustomThing]` where some general lazy facility or indirection is indicated by the '#' (just a placeholder for this comment, not a proposal). But if that comes about, it should be available everywhere, not only in annotations.

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