interfaces01.go

package main
import (
	"fmt"
	"math"
)

type geometry interface {
	area() float64
	perim() float64
}

type rect struct {
	width, height float64
}

type circle struct {
	radius float64
}

func (r rect)  area() float64 {
	return r.width * r.height
}

func (r rect) perim() float64 {
	return 2 * r.width + 2 * r.height 
}

func (c circle) area() float64 {
	return math.Pi * c.radius * c.radius
}

func (c circle) perim() float64 {
	return  2 * math.Pi * c.radius
}


func measure(g geometry) {
	fmt.Println(g)
	fmt.Println(g.area())
	fmt.Println(g.perim())
}

func main() {

	r := rect{width: 3, height: 4}
	c := circle{ radius: 5 }

	measure(r)
	measure(c)
}