[Go] IPoint interface demo.

package main

import (
    "fmt"
)

type IPoint interface {
    X() float64
    Y() float64
    SetX(float64)
    SetY(float64)
}

type Point struct {
    x float64
    y float64
}

func NewPoint(x float64, y float64) *Point {
    p := new(Point)

    p.SetX(x)
    p.SetY(y)

    return p
}

func (p *Point) X() float64 {
    return p.x
}

func (p *Point) Y() float64 {
    return p.y
}

func (p *Point) SetX(x float64) {
    p.x = x
}

func (p *Point) SetY(y float64) {
    p.y = y
}

type Point3D struct {
    // Point is embedded
    Point
    z float64
}

func NewPoint3D(x float64, y float64, z float64) *Point3D {
    p := new(Point3D)

    p.SetX(x)
    p.SetY(y)
    p.SetZ(z)

    return p
}

func (p *Point3D) Z() float64 {
    return p.z
}

func (p *Point3D) SetZ(z float64) {
    p.z = z
}

func main() {
    // Make a slice of IPoint
    points := make([]IPoint, 0)

    p1 := NewPoint(3, 4)
    p2 := NewPoint3D(1, 2, 3)
    // No error!
    points = append(points, p1, p2)

    for _, p := range points {
        fmt.Println(fmt.Sprintf("(%.2f %.2f)", p.GetX(), p.GetY()))
    }
}