[Python-Dev] Remove typing from the stdlib

[Paul Moore]

On 4 November 2017 at 03:53, Nick Coghlan <ncoghlan at gmail.com> wrote:
> If I understand correctly, a lot of the complexity in the current
> typing.py implementation is there to make isinstance and issubclass do
> something "useful" at runtime, and to allow generics to be used as
> base classes.
>
> If it wasn't for those design goals, then "typing.List[int]" could
> just return a lightweight instance of a regular class rather than a
> usable Python class definition.

+1 to this.

> If I'm right about that, then PEP 560's proposal to allow types to
> implement a hook that says "Replace me with this other object for
> runtime subclassing purposes" may be enough to let you delete most of
> the current code in the typing module - you'd just need to have
> isinstance and issubclass respect that new hook as well, and define
> the hooks as returning the relevant ABCs.

That would seem ideal to me.

Lukasz Langa said:
> So, the difference is in perceived usability. It's psychological.

Please, let's not start the "not in the stdlib isn't an issue" debate
again. If I concede it's a psychological issue, will you concede that
the fact that it's psychological doesn't mean that it's not a real,
difficult to solve, problem for some people? I'm also willing to
concede that it's a *minority* problem, if that helps. But can we stop
dismissing it as a non-existent problem?

Paul