如何在GO中获取指向接口的指针

Question

I would like to get rid of the variable temp in the following code:

type myinterface interface {
    f1()
}

type a struct {
    val int
}

type b struct {
    mi *myinterface
}

func (a) f1() {

}

    func demo() {

        a1 := a{3}
        var temp myinterface = a1
        b1 := b{&temp}
        fmt.Println(b1)

But if I try to write

b1 := b{&myinterface(a1)}

I get the message

cannot take the address of myinterface(a1) ( undefined )

what is the correct way to do this?

Update:

I did not a pointer to an interface, since an interface can hold a struct or a pointer to a struct, as also detailed in this question:

"<type> is pointer to interface, not interface" confusion

Answer 1

Let me know if this is what you are looking for: https://play.golang.org/p/ZGRyIqN7bPR

Full code:

package main

import (
  "fmt"
)

type myinterface interface {
  f1()
}

type a struct {
  val int
}

type b struct {
  mi myinterface
}

func (a) f1() {}


func main() {
  fmt.Println("Hello, playground")

  a1 := &a{3}
  b1 := b{a1}
  fmt.Println(b1)
}

You almost never need a pointer to an interface, since interfaces are just pointers themselves. So just change the struct b to:

 type b struct {
   mi myinterface
 }