如何获取类成员的类型注释？

Question

Consider the following code:

from typing import Optional

class Foo:
    def __init__(self):
        self.baz: Optional[int] = None

How do I find in code that baz has type Optional[int] ? If I do type(Foo().baz) , I only get None .

Answer 1

You could define the instance attribute type in the class body, as described in the PEP

from typing import Optional, get_type_hints

class Foo:
    baz: Optional[int]

    def __init__(self):
        self.baz = None


get_type_hints(Foo)

Out[26]: {'baz': typing.Union[int, NoneType]}

Note that typing.Union[int, NoneType] is the same as Optional[int] .