How to properly annotate a ContextManager in PyCharm?
This is a current PyCharm issue: PY-36444
A workaround for the issue is to rewrite an example code of:
from contextlib import contextmanager
@contextmanager
def generator_function():
yield "some value"
with generator_function() as value:
print(value.upper()) # no PyCharm autocompletion
to
from contextlib import contextmanager
from typing import ContextManager
def wrapper() -> ContextManager[str]:
@contextmanager
def generator_function():
yield "some value"
return generator_function()
with wrapper() as value:
print(value.upper()) # PyCharm autocompletion works
There is also an easier workaround of annotating the return type with ContextManager[str]
but there are multiple reasons against this:
- mypy will correctly emit errors for this annotation, as described in more detail in the PyCharm issue.
- this is not guaranteed to work in the future because PyCharm will hopefully fix the issue and therefore break this workaround
I believe you can use ContextManager
from typing
, e.g.:
import contextlib
from typing import ContextManager
from pathlib import Path
@contextlib.contextmanager
def temp_borders_file() -> ContextManager[Path]:
pass
with temp_borders_file() as borders_f:
borders_f # has type Path here