'How can I perform a type guard on a property of an object in Python

PEP 647 introduced type guards to perform complex type narrowing operations using functions. If I have a class where properties can have various types, is there a way that I can perform a similar type narrowing operation on the property of an object given as the function argument?

class MyClass:
    a: Optional[int]
    b: Optional[str]
    # Some other things

def someTypeGuard(my_obj: MyClass) -> ???:
    return my_obj.a is not None

I'm thinking it might be necessary for me to implement something to do with square brackets in type hints, but I really don't know where to start on this.

Sources

This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.

Source: Stack Overflow

Solution	Source

'How can I perform a type guard on a property of an object in Python

Sources

Related Questions