如何在python中定义最终的classvar变量

Question

正如您在PEP 526中所看到的，我们可以用ClassVar word定义静态变量类。如下

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

另一个键入功能，正如您在PEP 591中看到的，我们可以用Final word定义常量（只读）变量，如下所示

class Connection:
    TIMEOUT: Final[int] = 10

我的问题是如何结合这两个词来表示我的类静态变量是Final

例如下面的代码是否有效

class Connection:
    TIMEOUT: Final[ClassVar[int]] = 10

Answer 1

从PEP-591：

Type checkers should infer a final attribute that is initialized in a class body as being a class variable. Variables should not be annotated with both ClassVar and Final.

所以你可以使用：

class Connection:
    TIMEOUT: Final[int] = 10