Add a FloatInt (float | int) type alias - #189
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PEP 484's numeric tower makes `int` assignable to any `float`-annotated parameter, attribute or variable, even under `mypy --strict`, while at runtime `isinstance(1, float)` is `False`. A plain `float` annotation is therefore a lie: it silently admits values that fall through an apparently exhaustive `match … case float():` into `assert_never()`, and that lack `float`-only methods like `hex()`. There is no clean fix in Python, and the alternatives were all measured or analyzed and rejected: coercing at ingress costs ~2.3x on the construction of hot-path types, structural `Protocol` tricks don't close the widened variable and `Sequence` covariance holes, and widening `match` arms one by one leaves the annotation lying. So stop lying instead and spell out what PEP 484 actually admits, at zero runtime cost. The docstring example is mirrored as a regular test because the example linter only extracts module, class and function docstrings, so an example documenting a module attribute is never checked. Signed-off-by: Leandro Lucarella <luca-frequenz@llucax.com>
The change is a pure widening with no effect on callers: `int` arguments were already accepted by type checkers via the numeric tower and already handled correctly by `math.isclose()`, the annotation just didn't admit it. Making it explicit means readers no longer have to guess whether integers are supported. Signed-off-by: Leandro Lucarella <luca-frequenz@llucax.com>
Signed-off-by: Leandro Lucarella <luca-frequenz@llucax.com>
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I will make a v1.4.0 release after this is merged. |
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This is a port of the
FloatInttype alias in he full analysis is recorded in frequenz-floss/frequenz-client-common-python#181. Refer to frequenz-floss/frequenz-client-common-python#250 for details.Fixes #181.