go通过反射替换任意变量的函数

patchVariable.go

func TestH(t *testing.T) {
 say := func() {
  fmt.Println("say")
 }
 rec := patchFunction(&say, func() { fmt.Println("replace") })
 say()
 rec()
 say()
}

func patchFunction(item interface{}, new interface{}) func() {
 old := reflect.ValueOf(item).Elem().Interface()
 rec := func() {
  reflect.ValueOf(item).Elem().Set(reflect.ValueOf(old))
 }
 reflect.ValueOf(item).Elem().Set(reflect.ValueOf(new))
 return rec
}