get_return_type¶

privex.helpers.common.get_return_type(f: callable) → Optional[Union[type, object, callable]][source]¶

Extract the return type for a function/method. Note that this only works with functions/methods which have their return type annotated, e.g. def somefunc(x: int) -> float: return x * 2.1

Attention

If you want to extract a function/method return type and have any Generic typing types simplified down to their native Python base types (important to be able to compare with isinstance() etc.), then you should use extract_type() instead (handles raw types, objects, and function pointers)

Example 1 - Extracting a generic return type from a function:

>>> def list_wrap(v: T) -> List[T]:
...     return [v]
...
>>> rt = get_return_type(list_wrap)
typing.List[~T]
>>> rt._name            # We can get the string type name via _name
'List'
>>> l = rt.__args__[0]  # We can access the types inside of the [] via .__args__
~T
>>> l.__name__          # Get the name of 'l' - the type inside of the []
'T'

Example 2 - What happens if you use this on a function/method with no return type annotation?

The answer is: nothing - it will simply return None if the function/method has no return type annotation:

>>> def hello(x):
...     return x * 5
>>> repr(get_return_type(hello))
'None'

Parameters: f (callable) – A function/method to extract the return type from
Return return_type: The return type, usually either a type or a object