Go Example--接口

package main

import (
	"math"
	"fmt"
)

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

//rect实现接口
type rect struct {
	width,height float64
}
//cicle实现接口
type cicle 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 cicle)area() float64 {
	return math.Pi * c.radius*c.radius
}

func (c cicle)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:=cicle{radius:5}

	//rect cicle都可以赋值给接口
	measure(r)
	measure(c)
}