from __future__ import annotations
from functools import singledispatch
from typing import Any
from collections.abc import MutableMapping
@singledispatch
def foo(x: Any, y: MutableMapping) -> int:
raise NotImplementedError
@foo.register
def _(x: int, y: MutableMapping) -> int:
return x$ python --version
Python 3.10.14
$ ruff --version
0.4.5
$ python bug.py # no issues
$ ruff check bug.py
bug.py:6:29: TCH003 Move standard library import `collections.abc.MutableMapping` into a type-checking block
Found 1 error.
No fixes available (1 hidden fix can be enabled with the `--unsafe-fixes` option).
$ ruff check --unsafe-fixes bug.py
Found 1 error (1 fixed, 0 remaining).
$ python bug.py
Traceback (most recent call last):
File "/home/coder/doodles/python/ruff-check/bug.py", line 17, in <module>
def _(x: int, y: MutableMapping) -> int:
File "/home/coder/.conda/envs/rapids/lib/python3.10/functools.py", line 871, in register
argname, cls = next(iter(get_type_hints(func).items()))
File "/home/coder/.conda/envs/rapids/lib/python3.10/typing.py", line 1871, in get_type_hints
value = _eval_type(value, globalns, localns)
File "/home/coder/.conda/envs/rapids/lib/python3.10/typing.py", line 327, in _eval_type
return t._evaluate(globalns, localns, recursive_guard)
File "/home/coder/.conda/envs/rapids/lib/python3.10/typing.py", line 694, in _evaluate
eval(self.__forward_code__, globalns, localns),
File "<string>", line 1, in <module>
NameError: name 'MutableMapping' is not defined
Consider:
With the following ruff configuration
ruff suggests that (TCH003)
MutableMappingbe moved into aTYPE_CHECKINGblock, however, this is an invalid fix since the singledispatch registration needs access to the types at runtime.