Python 带可选变量的模式匹配

Question

I'm using mypy and I have two classes:

class Student:
    first_name: str
    ...

class City:
    id: int
    name: str
    ...

I have some db function that fetch the data and I end up with these two variables:

student: Optional[Student] = ...
city: Optional[City] = ...

I want to do pattern match for each case of None or non-None data of both variables.

I want to do different things for each case, this way:

match student, city:
    case None, None:
        output = "they all none"
    case Student(), City():
        output = f"student: {student.first_name} lives in {city.name}"
    case _, _:
        output = "one of them is none..."

But mypy doesn't recognize student and city as non-None in the second case. I don't want to use # type: ignore

Answer 1

EDITED to consider user19077881 suggestion. I would go with the classic ifs:

if student==None and city==None:
    output = "they all none"
elif student==None or city==None:
    output = "one of them is none..."
else:
    output = f"student: {student.first_name} lives in {city.name}"