typing.ClassVar

from typing import ClassVar

用法：

class Starship:
    stats: ClassVar[dict[str, int]] = {} # class variable
    damage: int = 10                     # instance variable

ClassVar 用于指示一个变量是类变量而非实例变量，从而提高代码的可读性。

ClassVar 仅用于类型注解，不影响程序执行。

ClassVar 本身不是一个类，不能用于 isinstance() 或者 issubclass() 方法。

以下为原文：

Special type construct to mark class variables.

An annotation wrapped in ClassVar indicates that a given
attribute is intended to be used as a class variable and
should not be set on instances of that class.

Usage::

class Starship:
stats: ClassVar[dict[str, int]] = {} # class variable
damage: int = 10                     # instance variable

ClassVar accepts only types and cannot be further subscribed.

Note that ClassVar is not a class itself, and should not
be used with isinstance() or issubclass().