typeddict: clarify that .get() with an unknown literal key is not an error#2312
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ashishpatel26 wants to merge 2 commits into
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typeddict: clarify that .get() with an unknown literal key is not an error#2312ashishpatel26 wants to merge 2 commits into
ashishpatel26 wants to merge 2 commits into
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…error
The spec's `.get()` bullet only specified the return type for the
variable-key case ("cannot be determined statically"), leaving the
literal-key cases undefined. Expand the bullet to cover all three
cases:
1. Known literal key — return type is ``T | None`` for non-required
keys; type checkers may return ``T`` or ``T | None`` for required.
2. Unknown literal key — NOT an error; return type is the union of
all value types combined with ``None``.
3. Non-literal key — unchanged: union of all value types | ``None``.
The conformance test had ``movie.get("other") # E?``, which the runner
treats as "optional" (neither requiring nor forbidding an error). Now
that the spec is explicit, change it to a plain call with no error
marker, and update the surrounding comments to quote the spec.
pycroscope is the only checker that flags ``movie.get("other")`` as an
error; its TOML now shows Partial/Fail reflecting this non-conformance.
All other checker TOMLs updated for the +2-line shift.
Fixes: python#2054
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Summary
Fixes #2054.
The spec's
.get()exception bullet only specified the return type for the variable-key case ("cannot be determined statically"), leaving two cases undefined:d.get("known_key")— a literal key that exists in the TypedDictd.get("unknown_key")— a literal key not defined in the TypedDictThis PR expands the bullet to cover all three cases explicitly:
T | Nonefor non-required keys; type checkers may returnTorT | Nonefor required.None.None.Conformance test changes
The test had
movie.get("other") # E?— the# E?marker is a wildcard that treats errors as optional (neither requiring nor forbidding one). Now that the spec is explicit, this becomes a plain call with no error marker.pycroscopeis the only checker that currently flagsmovie.get("other")as an error; its TOML is updated toPartial/Fail. All other checker TOMLs are updated for the +2-line shift caused by replacing the "not clear" comments with spec-quoting comments.Files changed
docs/spec/typeddict.rst— expanded.get()bullet with three explicit sub-casesconformance/tests/typeddicts_operations.py— removed# E?, updated commentsconformance/results/*/typeddicts_operations.toml— updated line numbers; pycroscope updated to Partial/FailTest plan
conformance_automated = "Fail"result for this test (as expected)validate_results.pypasses (all Fail results have explicitconformantfield)