bpo-46414: Add typing.reveal_type #30646
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Part of the documentation was taken from mypy: https://mypy.readthedocs.io/en/stable/common_issues.html#reveal-type
Misc/NEWS.d/next/Library/2022-01-17-10-00-02.bpo-46414.Ld0b_y.rst
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Thank you! This solves my old pain with redefining from typing import TYPE_CHECKING
if not TYPE_CHECKING:
reveal_type = print |
Co-authored-by: Nikita Sobolev <mail@sobolevn.me>
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Hold on. This feels awkward, since previously this was a builtin. I don’t want to have to import it. |
Type checkers would still allow using it without the import. You'll have the option to import it if you want to run your code or document to readers what |
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It needs more discussion. Please wait until I have a keyboard. |
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No hurry! I also opened a thread on typing-sig about this, that's probably the best place to discuss how it should work. |
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@gvanrossum based on the discussion on typing-sig, are you satisfied with this change now? I'm planning to also add |
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Wait, I didn't address Nikita's review yet. |
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Did we bikeshed yet whether it should write to stdout or stderr? |
No, though there have been some suggestions about the output format; I just sent a typing-sig email about that too. Personally I don't care much but I'd like to keep it simple. |
I'm just thinking that sending the output to stderr would be more in line with the debug nature of the API. |
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Pushed a change to make it write to stderr instead. |
Co-authored-by: Guido van Rossum <guido@python.org>
| @@ -2667,3 +2668,23 @@ class re(metaclass=_DeprecatedType): | |||
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| re.__name__ = __name__ + '.re' | |||
| sys.modules[re.__name__] = re | |||
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| def reveal_type(obj: T, /) -> T: | |||
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Do we use type hints in typing.py?
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If this is merged, we will :). I don't see any reason not to, especially in cases like this where the type is simple and helps document the behavior.
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There are type annotations in a few lines of typing.py:
Line 2531 in 270a091
It's just about the only module in the stdlib in which I've spotted any type annotations other than importlib :)
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@gvanrossum do you think this is ready to merge now? The discussion on typing-sig has died down. (You added the "Do not merge" label a while ago.) I think the other new function PRs are also ready, but I can ping you on those later. |
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@gvanrossum: Please replace |
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Should probably post the resolution to typing-sig. |
Co-authored-by: Nikita Sobolev <mail@sobolevn.me>
Part of the documentation was taken from mypy:
https://mypy.readthedocs.io/en/stable/common_issues.html#reveal-type
https://bugs.python.org/issue46414