Go中的重新分配方法

Question

Suppose I have the following:

package main

import "fmt"

type I1 interface {
    m1()
}

func f1() {
    fmt.Println("dosomething")
}

func main() {
    var obj I1
    obj.m1 = f1

    obj.m1()
}

This generates the error

./empty.go:16: cannot assign to obj.m1

Why can't I assign to 'method fields'?

In C, I can just pass around function pointers. What is the equivalent in Go?

Answer 1

You can't assign a function to an interface, you can do it for a struct, for example:

type S1 struct {
    m1 func()
}

func f1() {
    fmt.Println("dosomething")
}

func main() {
    var obj S1
    obj.m1 = f1

    obj.m1()
}

// another example

type I1 interface {
    m1()
}

type S1 struct {}

func (S1) m1() {
    fmt.Println("dosomething")
}

type S2 struct { S1 }

func (s S2) m1() {
    fmt.Println("dosomething-2")
    //s.S1.m1() //uncomment to call the original m1.
}

func doI1(i I1) {
    i.m1()
}

func main() {
    doI1(S1{})
    doI1(S2{S1{}})
}

<kbd>play</kbd>