Add stubs for importlib.(resources.)readers
#10928
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I'm not sure why 8232196 was needed. I thought both |
| def __init__(self, loader, module: str) -> None: ... | ||
| def open_resource(self, resource: str) -> BufferedReader: ... | ||
| def is_resource(self, path: StrPath) -> bool: ... | ||
| def files(self): ... |
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This obviously returns a zipfile.Path at runtime. Unfortunately, if you add that annotation right now, mypy complains:
stdlib\importlib\readers.pyi:39: error: Return type "Path" of "files" incompatible with return type "Traversable" in supertype "TraversableResources" [override]
This points to an error either in our zipfile stubs or in our importlib.(resources.)abc stubs. Type checkers should probably understand zipfile.Path as being a subtype of Traversable; I believe that's the intention of the authors of these modules.
Anyway, that looks non-trivial to fix, so I'd rather defer it to another PR for now.
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| else: | ||
| def joinpath(self, child: str) -> abc.Traversable: ... # type: ignore[override] | ||
| __truediv__ = joinpath | ||
| def open(self, *args: Never, **kwargs: Never) -> NoReturn: ... # type: ignore[override] |
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| def open(self, *args: Never, **kwargs: Never) -> NoReturn: ... # type: ignore[override] | |
| def open(self, *args: Unused, **kwargs: Unused) -> NoReturn: ... # type: ignore[override] |
Never would disallow arguably allowed calls like .open("r") (even if those always raise an exception, of course).
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Yes, that was a deliberate choice... I thought maybe it would be useful for type checkers to warn you if you provided arguments to this function. Since it always fails at runtime, it seems like you're probably making a mistake if you're passing arguments to it?
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But that should already be caught by the NoReturn.While this is a far-fetched example (using a non-existent typing feature), this disallows things like this:
trav_open: SignatureOf[Traversible.open] = MultiplexedPath.openI wonder why no type checker complains about using Never, since this breaks Traversible's contract.
That said, I don't feel strongly about this.
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But that should already be caught by the
NoReturn
If we only have the NoReturn return annotation, type checkers will only complain when you call this method if you have mypy's --warn-unreachable setting turned on (or the equivalent setting in other type checkers), and most people don't, unfortunately. Whereas annotating the arguments with Never means you'll get an error from the type checker even if you only have the default settings enabled.
I'll concede that this is a bit of a hack, and that we're really working around the lack of something like python/typing#1043 -- but I think it's useful for the time being
Co-authored-by: Sebastian Rittau <[email protected]>
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Diff from mypy_primer, showing the effect of this PR on open source code: pytest (https://github.com/pytest-dev/pytest)
+ src/_pytest/assertion/rewrite.py:295: error: Unused "type: ignore" comment [unused-ignore]
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The annotations are incomplete. The module is somewhat poorly documented, and I wanted to defer anything too complex to future PRs, so that this was easier to review