如何比较功能类型的相等性？

Question

I am doing some testing and trying to test for equality of some function types. I have https://play.golang.org/p/GeE_YJF5lz :

package main

import (
    "fmt"
    "reflect"
)

type myStruct struct {
    f []someFunc
}

type someFunc func(a string) bool

var sf1 someFunc = func(a string) bool {
    return true
}

var sf2 someFunc = func(a string) bool {
    return false
}

func main() {
    a := []someFunc{sf1, sf2}
    b := []someFunc{sf1, sf2}

    fmt.Println(reflect.DeepEqual(a, b)) // false

    m := &myStruct{
        f: []someFunc{sf1, sf2},
    }

    n := &myStruct{
        f: []someFunc{sf1, sf2},
    }

    fmt.Println(reflect.DeepEqual(m, n)) // false
}

I haven't been able to find anything in the docs about comparing functions and know I must be missing something important as to why reflect.DeepEqual doesn't work for them properly.

Answer 1

You can compare function like this, Read more about the representation of functions here: http://golang.org/s/go11func

func funcEqual(a, b interface{}) bool {
    av := reflect.ValueOf(&a).Elem()
    bv := reflect.ValueOf(&b).Elem()
    return av.InterfaceData() == bv.InterfaceData()
}

For example: This is just an idea for your start point.

func main() {
    a := []someFunc{sf1, sf2}
    b := []someFunc{sf1, sf2}

    for idx, f := range a {
        fmt.Println("Index: ", idx, funcEqual(f, b[idx]))
    }
}

Output:

Index:  0 true
Index:  1 true

Play link: https://play.golang.org/p/6cSVXSYfa5