gh-107155: Fix help(lambda_func) when lambda_func has `__annotati…

[Eclips4]

...ons__`

I cannot find any example with parenthesis in signature of lambda 😄 .

• Issue: help() output of lambda with manually set __annotations__ is one char off #107155

[Eclips4]

Thanks for your help @AA-Turner !

Is there anything else that needs to be done? Also, I think this kind of PR doesn't need a NEWS entry.

[AlexWaygood]

Also, I think this kind of PR doesn't need a NEWS entry.

Here's how to think about whether a bugfix PR deserves a news entry: does the PR fix a bug that users have noticed? If so, users deserve to know about it being fixed, so it should have a news entry. If not, the PR should be closed, as users won't notice the change being made, which makes the PR have very limited value.

In this case, a user reported the bug on the GitHub issue tracker, so at least one user will notice the change. As such, it definitely deserves a news entry :)

[AA-Turner]

I'd agree with Alex, this is visible to end-users (although very rare!). Something that outlines that help and pydoc now correctly display lambdas with return annotations would be enough.

A

[Eclips4]

After your words, I agree that this PR needs a NEWS entry, thanks for thoroughly explanation!

I wrote some lines, please, check it.

[AA-Turner]

Thanks!

A

[Eclips4]

Now I'm have resolved the merge conflict.

[serhiy-storchaka]

I do not like modification of the original object. It is not thread-safe. It does not work if __annotations__ is read-only. It does not restore {'return': None}.

Maybe just keep the parentheses if the lambda object has annotations? In any case this is not a valid Python syntax.

[Eclips4]

I do not like modification of the original object. It is not thread-safe. It does not work if __annotations__ is read-only. It does not restore {'return': None}.

Maybe just keep the parentheses if the lambda object has annotations? In any case this is not a valid Python syntax.

All of your points makes sense to me, thanks for them! I've made changes, please take a look at them :)
Altough, there's one question: now for lambdas without any params but with __annotations__ = {"return": int} help looks like that:

Help on function <lambda> in module __main__:

<lambda> lambda () -> int

Is it okay or we should change it?

[serhiy-storchaka]

lambda with annotations can't be expressed in Python syntax anyway. At least it now has balanced parentheses and does not truncate words.

[miss-islington-app]

Thanks @Eclips4 for the PR, and @serhiy-storchaka for merging it 🌮🎉.. I'm working now to backport this PR to: 3.11, 3.12.
🐍🍒⛏🤖

[miss-islington-app]

Sorry, @Eclips4 and @serhiy-storchaka, I could not cleanly backport this to 3.12 due to a conflict.
Please backport using cherry_picker on command line.

cherry_picker b9a9e3dd62326b726ad2e8e8efd87ca6327b4019 3.12

[miss-islington-app]

Sorry, @Eclips4 and @serhiy-storchaka, I could not cleanly backport this to 3.11 due to a conflict.
Please backport using cherry_picker on command line.

cherry_picker b9a9e3dd62326b726ad2e8e8efd87ca6327b4019 3.11

[bedevere-app]

GH-115612 is a backport of this pull request to the 3.12 branch.

[bedevere-app]

GH-115613 is a backport of this pull request to the 3.11 branch.