Does a "with" statement support type hinting?

Question

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.

Answer 1

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     [...] 

Answer 2

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: ...