I'm playing around with trying to understand how to introspect typehints in Python, and I can't figure out how to compare hints at runtime
For example, I have two functions
def foo() -> List[str]:
...
def bar(values:List):
...
and I want to check that the output of foo() is compatible with the expected input of bar(). With some introspection I can get to the point where I can say
>>> print(return_type, expected_type)
typing.List[str] typing.List
and I want to compare these two types. Clearly a function that will accept any kind of list will accept a list of of strings, so I should be able to say that typing.List[str] is consistent with typing.List I tried
return_type == expected_type
isinstance(return_type, expected_type)
issubclass(return_type, expected_type)
return_type <= expected_type
The first two return False, the last two throw TypeErrors.
What is the correct way to compare these two type hints?
And yes, I know there are packages available to do this kind of thing, but my goal is more to understand how it works internally.