methods.go

package main

import "fmt"

type rect struct {
	width, height int
}

// The area method has a receiver type of *rect
func (r *rect) area() int {
	return r.width * r.height
}

// Methods can be defined for either pointer or
// value receiver types. Here is a value receiver.
func (r rect) perim() int {
	return 2*r.width + 2*r.height
}

func main() {

	r := rect{width: 10, height: 5}

	fmt.Println("area: ", r.area())
	fmt.Println("perim: ", r.perim())

	// Go automatically handles conversion between values and
	// pointers for method calls. You may want to use a pointer
	// receiver type to avoid copying on method calls or to allow
	// the method to mutate the receiving struct.
	rp := &r
	fmt.Println("area: ", rp.area())
	fmt.Println("perim: ", rp.perim())
}