How to add type hinting to "class" type in python

Question

# Java
public <T> T findById(String id, Class<T> clazz)

How should the Class<T> type in the above Java method signature be represented by Python type hint?

# Python
def find_by_id(id: str, clazz: ???) -> T

Not a dupe IMO. That question is, at best, ambiguous about whether it asks for the instance or the class. This one is explicit. — kojiro
– kojiro, Commented Nov 3, 2019 at 17:02

kojiro · Accepted Answer · 2023-08-07 13:05:26Z

6

To annotate the type of a class itself, use Type.

class AClass:
    ...


def a_function(a_string: str, a_class: type[AClass]) -> None:
    ...

Since a class is a type, the class name can be an annotation itself:

def a_class_factory(a_class: type[AClass], *args, **kwargs) -> AClass:
    return a_class(*args, **kwargs)

answered Nov 2, 2019 at 16:36

kojiro

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1 Comment

since Python 3.9, Type is deprecated and type should be used now.