带有用户定义类的类型提示

Question

似乎找不到确切的答案。我想为一个函数做一个类型提示，该类型是我定义的某个自定义类，称为CustomClass()。

然后让我们假设在某个函数中，调用它FuncA(arg)，我有一个名为arg的参数。输入提示的正确方式是：

def FuncA(arg: CustomClass):

或者是：

def FuncA(Arg:Type[CustomClass]):？

Answer 1

如果arg接受CustomClass的实例，则前者是正确的：

def FuncA(arg: CustomClass):
    #     ^ instance of CustomClass

如果您希望类CustomClass本身（或子类型），则应编写：

from typing import Type  # you have to import Type

def FuncA(arg: Type[CustomClass]):
    #     ^ CustomClass (class object) itself

就像写在关于Typing的文档中一样：

class typing.Type(Generic[CT_co])

A variable annotated with C may accept a value of type C. In contrast, a variable annotated with Type[C] may accept values that are classes themselves - specifically, it will accept the class object of C.

文档包括一个带有int类的示例：

a = 3         # Has type 'int'
b = int       # Has type 'Type[int]'
c = type(a)   # Also has type 'Type[int]'