如何检查Go接口类型的变量是否具有实现它的某些结构类型？

Question

Lets say that I have the following:

type A Interface{
   ....
}

//Implements A
type B struct{
   ....
}

//Imlements A
type C struct{
   ....
}

And now I have a function which accepts variable of type A as an argument:

func Foo(obj A){
     if A is B{
          ....
     }else if A is C{
          ....
     }
}

And a main function:

func main(){

    b := B{}
    Foo(b)

}

How can I check if the argument passed to the function is actually type B?

Answer 1

Use a type switch as mentioned the tour page linked by @CeriseLimón.

func Foo(v A) {
    switch v := v.(type) {
    case B:
        // It's a B
    case C:
        // It's a C
    }
}

See it in action in the playground.