polymorphism.go

package main

import "fmt"

type Shaper interface {
	Area() int
}

type Rectangle struct {
	length, width int
}

func (r *Rectangle) Area() int {
	return r.length * r.width
}

type Square struct {
	length int
}

func (s *Square) Area() int {
	return s.length * s.length
}

func main() {
	//r := &Square{3}
	r := &Rectangle{4, 6}
	fmt.Println(r)
	s := Shaper(r)
	fmt.Println("Area : ", s.Area())
}