typing: improve type coverage in sqlalchemy.sql.base for issue #6810

[kapildagur]

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✅ typing: improve type coverage in sqlalchemy.sql.base for issue #6810

Overview

This pull request enhances the type coverage of the sqlalchemy.sql.base module as part of the gradual migration toward complete static typing under --strict mode (#6810).

The typing improvements were made with careful consideration of:

• Mypy --strict compatibility

• Runtime behavior preservation

• Avoidance of external API typing regressions

• Maintaining test and slot safety

• Isolating downstream typing impact

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✅ Validation Checklist

Checkpoint	Status	Notes
mypy --strict	✅ Passed	No type errors in sql/base.py
flake8	✅ Passed	Style conforms to SQLAlchemy guidelines
black	✅ Passed	File formatted
zimports	✅ Passed	Imports sorted and grouped properly
slotscheck	✅ Passed	slots declared where expected
Unit tests	✅ Passed	No behavior changed; type-only changes
Type coverage increased	✅ Yes	sql/base.py is now strictly typed

[CaselIT]

great work. I've left some comments but the general code is great, thanks

[kapildagur]

Hii @CaselIT ,

While testing the latest changes, I noticed that an unused # type: ignore in selectable.py (line 1349) is causing a mypy --strict error.

This is currently breaking the GitHub workflow for the raised PR. Would it be okay to remove this in the same PR to keep the CI passing cleanly?

Just wanted to confirm before making that change. Thanks!

[CaselIT]

Sure thanks

[kapildagur]

Hi @CaselIT,

I've made all the suggested changes and also fixed the GitHub workflow issue by removing the unused # type: ignore comment in selectable.py.

When you have a chance, please feel free to run the workflow and review the PR — let me know if there's anything else that needs adjustment or improvement.

Thanks again for your guidance!

[sqla-tester]

OK, this is sqla-tester setting up my work on behalf of CaselIT to try to get revision 7374212 of this pull request into gerrit so we can run tests and reviews and stuff

[sqla-tester]

New Gerrit review created for change 7374212: https://gerrit.sqlalchemy.org/c/sqlalchemy/sqlalchemy/+/6028

[kapildagur]

Good Morning @CaselIT,

I checked the CI and noticed the Python 3.7 job is failing due to the use of Final, which was introduced in Python 3.8(docs).

To keep compatibility, I’ll remove the Final annotations from this PR. Just wanted to confirm that approach before pushing the update.

[CaselIT]

It's fine to keep, I 'll adjust as needed in gerrit next. Thanks for your contribution!

[sqla-tester]

Gerrit review https://gerrit.sqlalchemy.org/c/sqlalchemy/sqlalchemy/+/6028 has been merged. Congratulations! :)

[sqla-tester]

Michael Bayer (zzzeek) wrote:

this needs to pass pep484 in order to merge

View this in Gerrit at https://gerrit.sqlalchemy.org/c/sqlalchemy/sqlalchemy/+/6029

[kapildagur]

Hii @CaselIT,

I saw your recent commit on sql.base — thanks for pointing it out.

I was busy with exams for the last three weekends, so I couldn’t propose the PR as planned. I’m free now and will try to propose it this weekend.

[kapildagur]

This weekend I'm planning for sql.compiler, Waiting for your approval...
Thanks

[CaselIT]

sure

[sqla-tester]

Federico Caselli (CaselIT) wrote:

recheck pep484

View this in Gerrit at https://gerrit.sqlalchemy.org/c/sqlalchemy/sqlalchemy/+/6029

[sqla-tester]

Federico Caselli (CaselIT) wrote:

pep484 recheck

View this in Gerrit at https://gerrit.sqlalchemy.org/c/sqlalchemy/sqlalchemy/+/6029

[sqla-tester]

Gerrit review https://gerrit.sqlalchemy.org/c/sqlalchemy/sqlalchemy/+/6029 has been merged. Congratulations! :)