interface-values-with-nil.go

package main

import "fmt"

type I interface {
    M()
}

type T struct {
    S string
}

func (t *T) M(){
    if t == nil{
        fmt.Println("NIL")
        return
    }
    fmt.Println(t.S)
}

func describe(i I) {
    fmt.Printf("(%v, %T) \n", i,i)
}

func main(){
    var i I

    var t *T
    i = t
    describe(i)
    i.M()

    i = &T{"Hello"}
    describe(i)
    i.M()
}