Add typing_extensions.utils #45

srittau · 2022-05-21T17:20:25Z

Closes: #6

Closes: python#6

JelleZijlstra

Thanks! Some general feedback:

I don't like the ext name. It's short for "extension", so it's extensions to the extensions?
I'm worried making typing-extensions into a package will break some downstream use of the library. I suppose we could just put the new names into typing_extensions.py, and then we don't have to think about the ext name either.
With these additions, we should also provide better documentation. Maybe a page on typing.readthedocs.io.

src/typing_extensions/ext.py

JelleZijlstra · 2022-05-26T03:29:56Z

src/typing_extensions/ext.py

+        ...
+
+
+class SupportsRDivMod(Protocol[_T_contra, _T_co]):


This seems very obscure, and Python only uses it in two places. I think we can skip it.

In fact even SupportsDivMod (without the R) seems marginal; it's also only used twice in typeshed.

But it is used. I think it doesn't hurt to have them here instead of typing. In fact, for completeness and consistency's sake I think it will make sense in the long run to have protocols for the other arithmetic operators here.

I think SupportsRDivMod is okay, though I agree with @JelleZijlstra that it isn't really used much, so I'd also be fine with omitting it.

A lot of the other arithmetic dunders are quite tricky, though (BinOp dunders in general are quite tricky), due to the presence of the reflected dunders. It can be hard to predict when you actually need an object with an __add__ method, and when "anything with either an __add__ or an __radd__ method" will do. SupportsRichComparison in _typeshed is a really good example: it has to be a union of protocols to work and, although it works really well for loads of functions in typeshed, we still have to use a different union of protocols for the functions in _operator.pyi.

AlexWaygood

This looks great! I agree with @JelleZijlstra's points, however. On the naming, maybe typing_extensions.utils, on the grounds that these are small utilities that can be reused a bunch of times?

I'm also slightly nervous about including SupportsANext, given that sometimes you want a guarantee that __anext__ will be a coroutine method, and sometimes you don't (python/typeshed#7491). It might not be as easy to use as users expect.

srittau · 2022-05-27T08:22:10Z

I like utils as a sub-package name. I'd still want to use a sub-package, to clearly distinguish between back-/forwards ports and real "extensions". I will test a package version of typing_extensions later with mypy, but apart from that what could realistically break?

srittau · 2022-05-27T09:39:47Z

I'm also slightly nervous about including SupportsANext, given that sometimes you want a guarantee that __anext__ will be a coroutine method, and sometimes you don't (python/typeshed#7491). It might not be as easy to use as users expect.

In cases, where __anext__() needs to return a coroutine, a type error would be reported, wouldn't it, so it's easy to spot. Maybe this is something we can point out in the documentation?

AlexWaygood · 2022-05-27T09:46:33Z

I'm also slightly nervous about including SupportsANext, given that sometimes you want a guarantee that __anext__ will be a coroutine method, and sometimes you don't (python/typeshed#7491). It might not be as easy to use as users expect.

In cases, where __anext__() needs to return a coroutine, a type error would be reported, wouldn't it, so it's easy to spot. Maybe this is something we can point out in the documentation?

I still think this would be somewhat surprising behaviour for users, but I'm okay with just adding a note to the documentation :)

AlexWaygood · 2022-05-27T09:52:35Z

I'd still want to use a sub-package, to clearly distinguish between back-/forwards ports and real "extensions".

I also really like the idea of a subpackage, FWIW!

srittau · 2022-06-03T08:48:57Z

So, any updates? Is the PR fine as it is or should I change things? In case it's considered a blocker, I can merge the subpackage, but I think that will cause more problems down the line, concerning maintainability/extensibility and distinction between typing backports and extensions.

JelleZijlstra · 2022-06-04T00:25:53Z

src/typing_extensions/utils.py

+
+from os import PathLike
+from typing import AbstractSet, Awaitable, Iterable, Tuple, TypeVar, Union
+from typing_extensions import Protocol, TypeAlias


Maybe add __all__?

JelleZijlstra · 2022-06-04T00:27:16Z

src/typing_extensions/utils.py

+        ...
+
+
+class SupportsDivMod(Protocol[_T_contra, _T_co]):


I still think we should drop the divmod protocols:

They're not widely used: in typeshed we only use them for divmod itself.

They're unintuitive in that divmod() normally returns a pair, but the protocols don't reflect that.

JelleZijlstra · 2022-06-04T00:28:35Z

README.md

@@ -144,4 +144,4 @@ These types are only guaranteed to work for static type checking.
 ## Running tests

 To run tests, navigate into the appropriate source directory and run
-`test_typing_extensions.py`.
+`test_typing_extensions/__init__.py`.


I can't comment there, but we should also mention the utils module in the README around line 34.

harahu · 2022-06-04T18:58:51Z

See the comments of @gvanrossum in #47 regarding the naming of the subpackage. typing_utils was suggested as a better alternative to utils.

harahu · 2022-08-26T20:10:19Z

What's the status on this PR? It seems somewhat stale.

hauntsaninja · 2022-08-26T20:51:52Z

At least from my perspective:
There's some stuff we should think through re: upstream typing.py, stability, versioning and type checker special casing.
I think there's a good chance that once we do that we find we may want a separate package, so to that extent ideally we'd resolve some of that before merging.
See my comments on the issue for more details: #6 (comment)

typing_extensions is a top 10 package on PyPI so it behooves us to be thoughtful, even if that constrains how fast we can move.

harahu · 2022-08-26T21:12:37Z

typing_extensions is a top 10 package on PyPI so it behooves us to be thoughtful, even if that constrains how fast we can move.

Not implying you should rush. Just couldn't find the reasoning for it being left in limbo in the comments here. Hoped for something explicit, like you just gave me. Appreciated.

JelleZijlstra · 2023-06-02T00:02:28Z

Closing this following the policy to only include things that are in CPython or in a PEP. Let's instead create a separate package for reusable types.

srittau added 5 commits May 21, 2022 19:06

Turn typing_extensions into a package

24a6581

Add typing_extensions.ext

e4da1dc

Closes: python#6

Skip .venv directories for flake8

d09c068

Python <= 3.8 fix

4f09778

flake8 fixes

ffb5908

JelleZijlstra reviewed May 26, 2022

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AlexWaygood reviewed May 26, 2022

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AlexWaygood mentioned this pull request May 27, 2022

Show type aliases in error messages python/mypy#12835

Open

srittau added 3 commits May 27, 2022 11:19

SupportsGetItem: Don't derive from Container

23c784b

Merge branch 'main' into ext

a9b06cf

Rename .exc to .utils

3c22f2a

srittau changed the title ~~Add typing_extensions.ext~~ Add typing_extensions.utils Jun 3, 2022

srittau mentioned this pull request Jun 3, 2022

Add a partial, covariant Mapping type #47

Closed

JelleZijlstra reviewed Jun 4, 2022

View reviewed changes

hauntsaninja mentioned this pull request Jun 4, 2022

Adding protocols and aliases from _typeshed to typing-extensions #6

Closed

AlexWaygood mentioned this pull request Aug 22, 2022

refactor: expand types in xml module python/typeshed#8590

Merged

JelleZijlstra closed this Jun 2, 2023

srittau deleted the ext branch June 2, 2023 08:27

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Add typing_extensions.utils #45

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Add typing_extensions.utils #45

Add typing_extensions.utils #45

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