golang geometry package

geometry.go

package geometry

import "math"

type Geom interface {
    Area() float64
}

type circle float64

func (self circle) Area() float64 {
    v := float64(self)
    return math.Pi * v * v
}

func NewCircle(r float64) Geom {
    return circle(r)
}

type rectangle struct {
    W, H float64
}

func (self *rectangle) Area() float64 {
    return self.W * self.H
}

func NewRectangle(w, h float64) Geom {
    return &rectangle{w, h}
}