Golang: Using structs as key for Maps

struct_as_map_key.go

package main

import "fmt"

type A struct {
	a, b int
}

func MapStructValAsKey(){
	// Notice: We are using value of `A`, not `*A`
	m1 := make(map[A]string)
	
	a1 := &A{0, 1}
	m1[*a1] = "01"
	
	a2 := &A{0, 1}
	
	// Succeeds because map is hashing with 
	// the `struct` value
	_, lookSucceed := m1[*a2]
	
	fmt.Println(m1, lookSucceed)
}

func MapStructPointerAsKey(){
	// Notice: We are using pointer of `*A`, not `A`
	m1 := make(map[*A]string)
	
	a1 := &A{0, 1}
	m1[a1] = "01"
	
	a2 := &A{0, 1}
	
	// Fails because map is hashing with 
	// the `struct` memory address
	_, lookSucceed := m1[a2]
	fmt.Println(m1, lookSucceed)
}

func main() {
	MapStructValAsKey()
	MapStructPointerAsKey()	
}

Output

map[{0 1}:01] true
map[0x104361c8:01] false

Go Play: Run it yourself here
http://play.golang.org/p/JC0a4GsaYO

You are using a pointer instead of a struct as the key

yeah.. name of this is misleading

You saved my day .... Thanks.