methods-with-pointer-receivers.go

package main

import (
    "fmt"
    "math"
)

type Vertex struct {
    X, Y float64
}

func (v * Vertex) Scale(f float64) {
    v.X = v.X * f
    v.Y = v.Y * f
}

func (v *Vertex) Abs() float64 {
    return math.Sqrt( v.X * v.X + v.Y * v.Y)
}

func main() {
	v := &Vertex{3, 4}
	fmt.Printf("Before scaling: %+v, Abs: %v\n", v, v.Abs())
	v.Scale(5)
	fmt.Printf("After scaling: %+v, Abs: %v\n", v, v.Abs())
}