method.go

package main

import (
	"fmt"
	"math"
)

type Vertex struct {
	X, Y float64
}

/*
Go does not have classes. However, you can define methods on types.

A method is a function with a special receiver argument.

The receiver appears in its own argument list between the func keyword and the method name.

In this example, the Abs method has a receiver of type Vertex named v.
*/

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

//Remember: a method is just a function with a receiver argument.
func Abs(v Vertex) float64 {
	return math.Sqrt(v.X*v.X + v.Y*v.Y)
}

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

func (v *Vertex) Scale2(f float64) {
	v.X = v.X * f
	v.Y = v.Y * f
}

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

	fmt.Println(Abs(v))

	v.Scale(10)
	fmt.Println(v.Abs())

	v.Scale2(10)
	fmt.Println(v.Abs())
}