Type hints with user defined classes

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]):?

The former is correct , if arg accepts an instance ofCustomClass:

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

In case you want the classCustomClass 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 withType[C] may accept values that are classes themselves - specifically, it will accept the class object ofC.

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]'
>

From: stackoverflow.com/q/44664040