Tip for golang recievers

recievertip.go

// http://play.golang.org/p/TC1PoskmV2
package main

import "fmt"

type Foo struct {
	n int
}

func (foo Foo) String() string {
	return fmt.Sprintf("&f == &foo is %v, foo.n = %d", &f == &foo, foo.n)
}

type Bar struct {
	m int
}

func (bar *Bar) String() string {
	if bar == nil {
		return "bar is nil"
	}
	return fmt.Sprintf("&b == &bar is %v, bar.m = %d", &b == bar, bar.m)
}

var f Foo
var b Bar

func main() {

	// Foo
	fmt.Println("foo1:", f)		// foo1
	f.n = 100
	fmt.Println("foo2:", f)		// foo2

	// Pointer of Foo
	var fp *Foo
	fmt.Println("foo3:", fp)	// foo3
	fp = &f
	fmt.Println("foo4:", fp)	// foo4

	fmt.Println()

	// Bar
	fmt.Println("bar1:", b)		// bar1
	b.m = 200
	fmt.Println("bar2:", b)		// bar2

	// Pointer of Bar
	var bp *Bar
	fmt.Println("bar3:", bp)	// bar3
	bp = &b
	fmt.Println("bar4:", bp)	// bar4
}

foo1: &f == &foo is false, foo.n = 0
foo2: &f == &foo is false, foo.n = 100
foo3:
foo4: &f == &foo is false, foo.n = 100

bar1: {0}
bar2: {200}
bar3: bar is nil
bar4: &b == &bar is true, bar.m = 200

foo1: &f == &foo is false, foo.n = 0
foo2: &f == &foo is false, foo.n = 100
foo3: <nil>
foo4: &f == &foo is false, foo.n = 100

bar1: {0}
bar2: {200}
bar3: bar is nil
bar4: &b == &bar is true, bar.m = 200