argparse: Use Literal for action & nargs add_argument parameter types#7329
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JelleZijlstra approved these changes Feb 20, 2022
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Looks good. The cwltool code found by mypy-primer can just add explicit annotations.
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Akuli commented Feb 20, 2022
We could try |
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According to mypy_primer, this change has no effect on the checked open source code. 🤖🎉 |
JukkaL added a commit to JukkaL/typeshed that referenced this pull request Apr 12, 2022
These were introduced in python#7329 and they cause false positives in code that used to be accepted before. There was a false positive in https://github.com/pycqa/pylint (encountered in python/mypy#12321) and I also saw false positives in an internal codebase. I suggest not using literal types here, since they can be kind of awkward to annotate in callers that don't pass a literal string. Rrequiring callers to write annotations like `Literal["?", "*", "+", "...", "A...", "==SUPPRESS=="]` is not very user friendly.
srittau pushed a commit that referenced this pull request Apr 13, 2022
These were introduced in #7329 and they cause false positives in code that used to be accepted before.
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As has previously been discussed in #6826 (comment) the
argparsemodule sometimes comparesargparse.SUPPRESSwithismeaningLiteral["==SUPPRESS=="]is not suited. This PR solves this usingNewType.As reported by mypy_primer the following fails with mypy:
because of:
This however seems to be due to a limitation in mypy not understanding that a newtype is backwards compatible with the original type as can be observed in the following example:
Mypy complains whereas Pyright says it's ok. With that in mind I think that the advantages of this PR (type safety against typos) outweigh the caused inconvenience (when reassigning SUPPRESS with mypy).