Inspect params and return types

Question

Is it possible using Python 3 syntax for declaring input parameters and return value types determine those types? Similarly to determining the number of parameters of a func

Answer 1

The typing module has a convenience function for that:

>>> import typing
>>> typing.get_type_hints(foo)
{'name': , 'return': }

(the documentation)

This is different from foo.__annotations__ in that get_type_hints can resolve forward references and other annotations stored in string, for instance

>>> def foo(name: 'foo') -> 'int':
...     ...
... 
>>> foo.__annotations__
{'name': 'foo', 'return': 'int'}
>>> typing.get_type_hints(foo)
{'name': , 'return': }

It will be especially useful in Python 4.0, because then all annotations will be stored in string form.