Binary comparison example

binary_comparison.go

const (
	roleUser = 1 << iota
	roleSuperUser
	roleAdmin
)

type User struct {
	name string
	role uint
}

func hasRole(user User, role uint) bool {
	return role & user.role == role
}

func addRole(user *User, role uint) {
	user.role = user.role | role
}

func delRole(user *User, role uint)  {
	user.role = user.role &^ role
}

func main() {
	user := User{"John Doe", roleUser }
	fmt.Printf("user has role roleUser? %v\n", hasRole(user, roleUser))
	fmt.Printf("user has role roleSuperUser? %v\n", hasRole(user, roleSuperUser))
	fmt.Printf("user has role roleAdmin? %v\n", hasRole(user, roleAdmin))

	addRole(&user, roleSuperUser)
	fmt.Printf("user has role roleUser? %v\n", hasRole(user, roleUser))
	fmt.Printf("user has role roleSuperUser? %v\n", hasRole(user, roleSuperUser))
	fmt.Printf("user has role roleAdmin? %v\n", hasRole(user, roleAdmin))


	delRole(&user, roleUser)
	fmt.Printf("user has role roleUser? %v\n", hasRole(user, roleUser))
	fmt.Printf("user has role roleSuperUser? %v\n", hasRole(user, roleSuperUser))
	fmt.Printf("user has role roleAdmin? %v\n", hasRole(user, roleAdmin))
}