duck.go

package main
import "fmt";

type Speaker interface {
	Speak() string;
}

type Person struct {
	name string;
}
func NewPerson(name string) (self *Person) {
	self = new(Person);
	self.name = name;
	return;
}
func (self *Person) Speak() string {
	return fmt.Sprintf("私の名前は%sです", self.name);
}
func (self *Person) String() string {
	return self.name;
}

type Dog struct {
	name string;
}
func NewDog(name string) (self *Dog) {
	self = new(Dog);
	self.name = name;
	return;
}
func (self *Dog) Speak() string {
	return "ワンワン!";
}
func (self *Dog) String() string {
	return self.name;
}

type Fish struct {
	name string;
}
func NewFish(name string) (self *Fish) {
	self = new(Fish);
	self.name = name;
	return;
}
func (self *Fish) String() string {
	return self.name;
}

func say( speaker Speaker ) {
	fmt.Printf("%s は言いました「%s」\n", speaker, speaker.Speak() );
}

func main() {
	alice := NewPerson("Alice");
	bob   := NewDog("Bob");
//	carol := NewFish("Carol");
	say(alice);
	say(bob);
//	say(carol);
}