[Python-Dev] Remove typing from the stdlib (original) (raw)

Paul Moore p.f.moore at gmail.com
Sat Nov 4 06:39:01 EDT 2017

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

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