问题：用户定义类的类型提示

似乎找不到确切的答案。我想为一个函数提供类型提示，该类型是我定义的一些自定义类，称为它CustomClass()。

然后让我们说在某个函数中调用它FuncA(arg)，我有一个名为的参数arg。键入提示的正确方法FuncA是：

def FuncA(arg: CustomClass):

或者是：

def FuncA(Arg:Type[CustomClass]):？

点击查看英文原文

Couldn’t seem to find a definitive answer. I want to do a type hint for a function and the type being some custom class that I have defined, called it CustomClass().

And then let’s say in some function, call it FuncA(arg), I have one argument named arg. Would the correct way to type hint FuncA be:

def FuncA(arg: CustomClass):

Or would it be:

def FuncA(Arg:Type[CustomClass]):?

回答 0

该前者是正确的，如果arg接受一个实例CustomClass：

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

如果您想要类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

就像在有关打字的文档中写的那样：

class typing.Type(Generic[CT_co])

带注释的变量C可以接受type的值C。相反，带注释Type[C]的变量可以接受本身是类的值 -具体地说，它将接受的类对象C。

该文档包含有关int该类的示例：

a = 3         # Has type 'int'
b = int       # Has type 'Type[int]'
c = type(a)   # Also has type 'Type[int]'
点击查看英文原文

The former is correct, if arg accepts an instance of CustomClass:

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

In case you want the class CustomClass itself (or a subtype), then you should write:

from typing import Type  # you have to import Type

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

Like it is written in the documentation about Typing:

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.

The documentation includes an example with the int class:

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