开始-通过反射附加到[] interface {}

Question

Without reflection it is possible to add multiple types to a list of type []interface{}. Like so:

package main

import "fmt"

func main() {
    var foo []interface{}
    foo = append(foo, "Test")
    foo = append(foo, "Foo")
    foo = append(foo, 10)
    fmt.Printf("%v
", foo)
}

Is this possible with reflection? I try the following but I get a panic saying: "panic: reflect.Set: value of type string is not assignable to type []interface {}"

package main

import (
    "fmt"
    "reflect"
)

func rf(inf interface{}) {
    val := reflect.Indirect(reflect.ValueOf(inf))
    field := val.FieldByName("Foo")
    rslice := reflect.MakeSlice(reflect.SliceOf(field.Type()), 0, 5)
    v := reflect.Indirect(reflect.ValueOf("Test"))
    rslice = reflect.Append(rslice, v)
}

func main() {
    var s struct {
        Foo []interface{}
    }
    rf(&s)
    fmt.Printf("%+v
", s)
}

Answer 1

The Foo field is already of type []interface{}, so SliceOf is creating a [][]interface{}, which is what causes the error you see.

Remove the SliceOf, and then use field.Set(rslice) to set the new value back to the struct field.

func rf(inf interface{}) {
    val := reflect.Indirect(reflect.ValueOf(inf))
    field := val.FieldByName("Foo")
    rslice := reflect.MakeSlice(field.Type(), 0, 5)
    v := reflect.Indirect(reflect.ValueOf("Test"))
    rslice = reflect.Append(rslice, v)
    field.Set(rslice)
}

http://play.golang.org/p/gWK3-cP_MN