08-methods.go

package main

import (
   "fmt"
   "math"
)

// Vertex type and methods
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)
}

// MyFloat type and methods
type MyFloat float64

func (f MyFloat) Abs() float64 {
   if f < 0 {
      return float64(-f)
   }
   return float64(f)
}

func main() {
   v := &Vertex{3, 4}
   v.Scale(5)
   fmt.Println(v, v.Abs())
}