Can you define the type hint for a variable defined with the with syntax?
with example() as x:
print(x)
I would like to type hint the above to say that x is a str (as an example).
The only work around that I've found is to use an intermediate variable, but this feels hacky.
with example() as x:
y: str = x
print(y)
I can't find an example in the typing documentation.
Usually type annotations are placed at the API boundaries. In this case the type should be inferred from example.__enter__. In case that function doesn't declare any types, the solution is to create a corresponding stub file in order to help the type checker infer that type.
Specifically this means creating a .pyi file with the same stem as the module from which Example was imported. Then the following code can be added:
class Example:
def __enter__(self) -> str: ...
def __exit__(self, exc_type, exc_value, exc_traceback) -> None: ...
PEP 526, which has been implemented in Python 3.6, allows you to annotate variables. You can use, for example,
x: str
with example() as x:
[...]
or
with example() as x:
x: str
[...]