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GeezerVison is showing github.com — fix: allow None for exc_tb in Traveller.__exit__ type annotations by madhavcodez · Pull Request #974 · python-pendulum/pendulum

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@madhavcodez

@madhavcodez madhavcodez commented Jun 27, 2026

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When a with block exits without an exception, CPython calls __exit__(None, None, None), so all three parameters must accept None. On the travellers, exc_type and exc_val were already optional, but exc_tb was typed as TracebackType without | None. A type checker correctly infers that the traveller is not a valid context manager, which produces the invalid-context-manager error on with pendulum.travel_to(...) reported in #973.

What changed

Annotate exc_tb as TracebackType | None in BaseTraveller.__exit__ and the time_machine-backed Traveller.__exit__ (the remaining Traveller subclasses inherit from BaseTraveller).

Closes #973. The underlying false-positive trigger is also tracked upstream at astral-sh/ty#3832.

Verification

Reproduced the invalid-context-manager diagnostic before the change and confirmed it clears afterward (reverting the annotation brings it back). ruff and mypy --strict stay clean. This is annotation-only with no runtime or behavior change, so no tests were added. Happy to add a CHANGELOG entry once this PR has a number if you would like one.

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@madhavcodez
fix: allow None for exc_tb in Traveller.__exit__ annotations
eda43e4 
CPython calls __exit__(None, None, None) when a with block exits without an
exception, so all three parameters must accept None. exc_type and exc_val were
already optional on the travellers, but exc_tb was annotated TracebackType
without | None, so a type checker infers the traveller is not a valid context
manager and reports invalid-context-manager on with pendulum.travel_to(...).

Annotate exc_tb as TracebackType | None in BaseTraveller.__exit__ and the
time_machine-backed Traveller.__exit__ (the other Traveller subclasses inherit
from BaseTraveller).

Closes python-pendulum#973
ashb
ashb approved these changes Jun 29, 2026
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@codspeed

codspeed Bot commented Jun 29, 2026

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Merging this PR will not alter performance

✅ 1 untouched benchmark

Comparing madhavcodez:fix/traveller-exit-type-973 (eda43e4) with master (b99bd14)

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@ashb
ashb merged commit 1d9e31a into python-pendulum:master Jun 29, 2026
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@ashb ashb ashb approved these changes

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Type checker thinks pendulum.travel_to() does not implement Traveller.__exit__

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@madhavcodez @ashb
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