nil example

package main

import (
  "fmt"
)

type IntWrapper struct {
	x int
}

func (this IntWrapper) value() int {
	return this.x
}

type Valler interface {
	value() int
}
//this will except a value, pointer, or nil without being specified in the function signature
func do_stuff_interface(x Valler) {
	fmt.Println(x.value())
}
//won't compile if you pass a pointer/nil
func do_stuff_safe(x IntWrapper) {
	fmt.Println(x.value())
}
//accepts nil, but at least x is marked as a pointer in the function signature
func do_stuff_unsafe(x *IntWrapper) {
	fmt.Println(x.value())
}

func main() {
	x := IntWrapper{x: 5}
	do_stuff_interface(&x)
	do_stuff_interface(x)
	do_stuff_unsafe(&x)
	do_stuff_safe(x)
	do_stuff_unsafe(nil)
	do_stuff_interface(nil)
}