goLang pass struct to function (args interface{})

Question

Here is my code http://play.golang.org/p/h0N4t2ZAKQ

package main

import (
    "fmt"
    "reflect"
)

type Msg struct {
    Message string
}

func print(y interface{}) {
    z, ok := y.(Msg)
    fmt.Println(reflect.TypeOf(z))
    fmt.Println("Value of ok ", ok)
    if ok {
        fmt.Println("Message is "+ z.Message)
    }
}

func main() {

    foo := new(Msg)
    foo.Message="Hello"
    fmt.Println("Messege in main "+foo.Message)
    print(foo)

}

When I run it z.Message does not print Hello Not sure why. Can someone clarify? Thanks in advance

Answer 1

Type of foo in your program is *Msg (pointer to Msg), not Msg. You need to cast y to *Msg in print (http://play.golang.org/p/MTi7QhSVQz):

z, ok := y.(*Msg)

Alternatively you can use Msg type for foo (http://play.golang.org/p/XMftjVtzBk):

foo := Msg{Message: "Hello"}

or

var foo Msg
foo.Message = "Hello"