Skip to content

/ cpython Public

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

bpo-41559: Implement PEP 612 - Add ParamSpec and Concatenate to typing #23702

Merged
merged 27 commits into from Dec 24, 2020
Merged

bpo-41559: Implement PEP 612 - Add ParamSpec and Concatenate to typing #23702

merged 27 commits into from Dec 24, 2020

Conversation

@Fidget-Spinner
Copy link
Contributor

@Fidget-Spinner Fidget-Spinner commented Dec 8, 2020 •
edited

Changes:

  • Add ParamSpec and Concatenate to typing.
  • Allow both in Callable
  • Allow ParamSpec in Generic
  • Treat ParamSpec as a TypeVar (add them to __parameters__ ) in:
    • typing generics
    • types.GenericAlias
  • Generics parameterized with ParamSpec and subscripted with lists should cast those lists to tuple:
    • typing.Generic
    • types.GenericAlias
  • Tests for ParamSpec
    • Test specified use cases with typing.Callable.
    • Test specified use cases with collections.abc.Callable.
    • Test user defined generics
    • TypeVar like substitution
  • Tests for Concatenate
  • Loosened Generic and GenericAlias type checks to allow for nearly anything.

Documentation will be another patch.

https://bugs.python.org/issue41559
@Fidget-Spinner
Add ParamSpec and Concatenate
219b4ee
@Fidget-Spinner
support ParamSpec in generics
a1c0d0a
@Fidget-Spinner
Add typing tests, disallow Concatenate in other types
7b3beab
@Fidget-Spinner
Add news
5dd3b44
@Fidget-Spinner Fidget-Spinner marked this pull request as ready for review Dec 9, 2020
gvanrossum
gvanrossum reviewed Dec 9, 2020
View changes
Copy link
Member

@gvanrossum gvanrossum left a comment

I'm sorry, I didn't get to the end of this review (not by far), but I have a few comments. Main thing though is, did you look at all the examples in PEP 612? It seems that for user-defined generic classes that have a ParamSpec parameter, things like X[int, P] are actually valid.

Maybe this indirectly also answers your question: I think that the ParamSpec should be included in __parameters__.

Also, I wonder if we could do less type checking at runtime rather than trying to be strict? I desperately want typing.py to shrink, not grow... :-)

Lib/typing.py Outdated Show resolved Hide resolved
Lib/typing.py Outdated Show resolved Hide resolved
Lib/typing.py Outdated Show resolved Hide resolved
Lib/typing.py Outdated Show resolved Hide resolved
Lib/typing.py Outdated Show resolved Hide resolved
Lib/typing.py Outdated Show resolved Hide resolved
Lib/typing.py Outdated Show resolved Hide resolved
Lib/typing.py Outdated Show resolved Hide resolved
Lib/test/test_typing.py Outdated Show resolved Hide resolved
@Fidget-Spinner
Copy link
Contributor Author

@Fidget-Spinner Fidget-Spinner commented Dec 9, 2020

Points taken. Sorry X[int, P] slipped my mind since I hadn't fixed __parameters__ yet.

D'oh, I just realised I answered my own question since we need __parameters__ to implement X[int, P] in the first place.

@Fidget-Spinner Fidget-Spinner marked this pull request as draft Dec 10, 2020
Fidget-Spinner and others added 4 commits Dec 10, 2020
@Fidget-Spinner @gvanrossum
Address some of Guido's review comments
59c0b20 
Co-Authored-By: Guido van Rossum <gvanrossum@users.noreply.github.com>
@Fidget-Spinner
remove extraneous empty lines
4c381b3
@Fidget-Spinner
Support ParamSpec in __parameters__ of typing and builtin GenericAlias
b36b62d 
also reduced runtime checks
@Fidget-Spinner
add tests for user defined generics
d09d088
@gvanrossum
Copy link
Member

@gvanrossum gvanrossum commented Dec 11, 2020

Let's wait until #23060 has landed and then see what adjustments this might need.

@Fidget-Spinner
Merge remote-tracking branch 'upstream/master' into pep612
0a19f34
@Fidget-Spinner
cast list to tuple done, loosened type checks for Generic
9727e2a
@Fidget-Spinner
loosen generics, allow typevar-like subst, flatten out args if Callable
cc7fc1c
@Fidget-Spinner
fix whitespace issue, cast list to tuple for types.GenericAlias
3e67f23
@Fidget-Spinner
convert list to tuples if substituting paramspecs in types.GenericAlias
d9baa1a
@Fidget-Spinner
done! flattened __args__ in substitutions for collections.abc.Callable
c4155b6
@Fidget-Spinner Fidget-Spinner marked this pull request as ready for review Dec 16, 2020
@Fidget-Spinner Fidget-Spinner requested a review from rhettinger as a code owner Dec 16, 2020
@Fidget-Spinner
fix repr problems, add repr tests
2dbf861
@Fidget-Spinner
Add another test for multiple chaining
87c2d19
@Fidget-Spinner
fix typo
2b09de6
@Fidget-Spinner Fidget-Spinner marked this pull request as draft Dec 17, 2020
@Fidget-Spinner
Clean up some comments
d980702
@Fidget-Spinner
remove stray whitespace
d6f777c
@gvanrossum
Copy link
Member

@gvanrossum gvanrossum commented Dec 23, 2020

Finally looking at this...

Actually I just realized PEP 612 doesn't explicitly say that ParamSpec should support TypeVar-like substitution. Maybe I over complicated things a little by allowing that in types.GenericAlias (just for collections.abc.Callable)?

Yeah, ParamSpec is super special, and you can't do anything with it that isn't explicitly mentioned in the PEP. So it's debatable whether Callable[P, int] should even have P in its __parameters__. Then again, for the simple case A = Callable[P, int] there's no reason why we couldn't allow A[[str, str]] and get Callable[[str, str], int] as the result. But type checkers wouldn't know what to do with that -- ParamSpec is a magic cookie.

So let's not worry about those clearly wrong cases.

@gvanrossum
Copy link
Member

@gvanrossum gvanrossum commented Dec 23, 2020 •
edited

Sorry, submitted too soon. (UPDATE: Not, I made a mistake -- or GitHub did. :-)

gvanrossum
gvanrossum reviewed Dec 23, 2020
View changes
Copy link
Member

@gvanrossum gvanrossum left a comment

Excellent work! Thanks for your perseverance. My feedback is mostly simple improvements.

Lib/_collections_abc.py Outdated Show resolved Hide resolved
Lib/_collections_abc.py Show resolved Hide resolved
Lib/test/test_typing.py Outdated Show resolved Hide resolved
Lib/test/test_typing.py Outdated Show resolved Hide resolved
Lib/test/test_typing.py Outdated Show resolved Hide resolved
Lib/typing.py Show resolved Hide resolved
Lib/_collections_abc.py Outdated Show resolved Hide resolved
Objects/genericaliasobject.c Outdated Show resolved Hide resolved
Objects/genericaliasobject.c Outdated
}
// convert all the lists inside args to tuples to help
// with caching in other libaries if substituting a ParamSpec
if (PyList_CheckExact(subst) && is_paramspec(arg)) {
Copy link
Member

@gvanrossum gvanrossum Dec 23, 2020

Why only do this for ParamSpec?

Copy link
Contributor Author

@Fidget-Spinner Fidget-Spinner Dec 23, 2020

I'm afraid of existing code relying on substituting typevars in genericalias with lists, then expecting that list to be inside __args__. Although in Python 3.9 that should be invalid, and the IDE/type checker should warn the users about that already.

If I just convert list to tuples for all cases, the C code will become way simpler :).

Copy link
Member

@gvanrossum gvanrossum Dec 23, 2020

There can't be much code yet relying about anything for GenericAlias -- it's new in 3.9. We could backport that particular behavior to 3.9.3 to ensure there won't be any more code relying on it. :-)

Objects/genericaliasobject.c Show resolved Hide resolved
Fidget-Spinner and others added 4 commits Dec 23, 2020
@Fidget-Spinner @gvanrossum
Address nearly all of Guido's reviews
9a8176b 
Co-Authored-By: Guido van Rossum <gvanrossum@users.noreply.github.com>
@Fidget-Spinner
more reviews; fix some docstrings, clean up code, cast list to tuple …
fa06838 
…by default
@Fidget-Spinner
remove uneeded tests copied over from typevar
b8672cd
@Fidget-Spinner
remove unused variable
51a463c
gvanrossum
gvanrossum reviewed Dec 23, 2020
View changes
Copy link
Member

@gvanrossum gvanrossum left a comment

Re: the 3.9 issues that you discovered: maybe create a PR for those first, land that in master and 3.9 branch, then merge master into this PR?

Lib/_collections_abc.py Outdated Show resolved Hide resolved
@Fidget-Spinner
Copy link
Contributor Author

@Fidget-Spinner Fidget-Spinner commented Dec 24, 2020 •
edited

Guido, thank you so much for all the time you've put into reviewing this PR! I learnt quite a bit about the typing module in the process :).

Re: the 3.9 issues that you discovered: maybe create a PR for those first, land that in master and 3.9 branch, then merge master into this PR?

Yeah I agree, I created #23915 for that. Once that one lands, I'll merge the changes in along with some of your suggestions.

@Fidget-Spinner
Merge remote-tracking branch 'upstream/master' into pep612
6d5b754
@Fidget-Spinner
merge length checking into _has_special_args too
c05d5d7
gvanrossum
gvanrossum approved these changes Dec 24, 2020
View changes
Lib/_collections_abc.py Outdated Show resolved Hide resolved
@gvanrossum
Update Lib/_collections_abc.py
c49ba30
@gvanrossum
Copy link
Member

@gvanrossum gvanrossum commented Dec 24, 2020

I think it’s ready!

@Fidget-Spinner Fidget-Spinner mentioned this pull request Dec 24, 2020
Merged
@gvanrossum
Copy link
Member

@gvanrossum gvanrossum commented Dec 24, 2020

@Fidget-Spinner Let me know if you agree.

@Fidget-Spinner
Copy link
Contributor Author

@Fidget-Spinner Fidget-Spinner commented Dec 24, 2020

@Fidget-Spinner Let me know if you agree.

Yes! Sorry, I thought you were going to merge it in so I was waiting too 😆 .

@gvanrossum
Copy link
Member

@gvanrossum gvanrossum commented Dec 24, 2020

I figured that was the case. :-)

@gvanrossum gvanrossum merged commit 73607be into python:master Dec 24, 2020
11 checks passed
@bedevere-bot
Copy link

@bedevere-bot bedevere-bot commented Dec 24, 2020

@gvanrossum: Please replace # with GH- in the commit message next time. Thanks!

@Fidget-Spinner
Copy link
Contributor Author

@Fidget-Spinner Fidget-Spinner commented Dec 24, 2020

@gvanrossum Oh dang I knew I had a hunch I missed something :/. I forgot to convert all lists to tuples in ga_new/setup_ga too (I did it only for getitem and co.). Well on the bright side, having that as a separate PR makes backporting to 3.9 easier if anything :), and anyways lists aren't valid in genericalias other than the Callable case (which we already have covered), so we won't have anything broken even without that in right now.

@Fidget-Spinner
Copy link
Contributor Author

@Fidget-Spinner Fidget-Spinner commented Dec 24, 2020

I'll fix that some other time, right now I'm celebrating 🥳

@Fidget-Spinner Fidget-Spinner deleted the pep612 branch Dec 24, 2020
@Fidget-Spinner Fidget-Spinner mentioned this pull request Dec 30, 2020
Merged
@Fidget-Spinner Fidget-Spinner mentioned this pull request Feb 14, 2021
Closed
adorilson added a commit to adorilson/cpython that referenced this issue Mar 13, 2021
@Fidget-Spinner @adorilson
bpo-41559: Implement PEP 612 - Add ParamSpec and Concatenate to typing (
41127ae 
python#23702)
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Reviewers

@gvanrossum gvanrossum

@ilevkivskyi ilevkivskyi

Assignees
No one assigned
Labels
CLA signed
Projects
None yet
Milestone
No milestone
4 participants
@Fidget-Spinner @gvanrossum @bedevere-bot @the-knights-who-say-ni