// +build OMIT 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()) }