Feature/replace list comp with generator

[zkneupper]

Replace list comprehensions with generator expressions inside str.join()

• Replace list comprehensions with generator expressions inside str.join() in several places in Lib/_pydecimal.py and Lib/argparse.py
• Replace a for loop with generator expression in Lib/ast.py

[the-knights-who-say-ni]

Hello, and thanks for your contribution!

I'm a bot set up to make sure that the project can legally accept this contribution by verifying everyone involved has signed the PSF contributor agreement (CLA).

Recognized GitHub username

We couldn't find a bugs.python.org (b.p.o) account corresponding to the following GitHub usernames:

@zkneupper

This might be simply due to a missing "GitHub Name" entry in one's b.p.o account settings. This is necessary for legal reasons before we can look at this contribution. Please follow the steps outlined in the CPython devguide to rectify this issue.

You can check yourself to see if the CLA has been received.

Thanks again for the contribution, we look forward to reviewing it!

[erlend-aasland]

Hi, and thank you for your interest in making CPython faster. Unfortunately, these changes are de-optimisations; list comprehensions are faster than generators. See Serhiy's review comment in #25798 (comment)

[isidentical]

This is making the code look worse for the _pad_whitespace. Thanks for the contribution (are these automated?) though please refrain from posting this kind of changes in the future for the different parts of the codebase. If you know a potential improvement, open an issue and send a PR for that issue only.

[bedevere-bot]

A Python core developer has requested some changes be made to your pull request before we can consider merging it. If you could please address their requests along with any other requests in other reviews from core developers that would be appreciated.

Once you have made the requested changes, please leave a comment on this pull request containing the phrase I have made the requested changes; please review again. I will then notify any core developers who have left a review that you're ready for them to take another look at this pull request.