19_defining_functions_as_methods.go

package main

import "fmt"

/*
-Go also supports the concept of methods. They are essentially functions but they
 are owned by some structure or other type
-In a more completely object-oriented language such as Java, you'd say that each method
 is a member of a class
-In Go, a method is a member of a type
*/

type Dog struct {
	Breed  string
	Weight int
	Sound  string
}

// -To add a method declare a separate function but add the type of the function's owner
//  before the function name with an identifier wrapped in parentheses
// -When the method is called, it'll receive a reference to the object that owns it
//  that'll be an instance of the Dog structure and it will have access to all of the fields
//  of that structure
// this method receives the copy of the Dog object every time it is called
// --the changes it makes does not reflect any changes on the original object
func (d Dog) Speak() {
	fmt.Println(d.Sound)
}

// this method receives the Dog object as a pointer
// --the changes it makes changes the contents of the object because the object gets passed bby its address
func (d *Dog) SpeakThreeTimes() {
	d.Sound = fmt.Sprintf("%v! %v! %v!", d.Sound, d.Sound, d.Sound)
	fmt.Println(d.Sound)
}

func main() {
	poodle := Dog{"Poodle", 37, "Woof"}
	fmt.Println(poodle)
	poodle.Speak()

	poodle.Sound = "Arf"
	poodle.Speak()

	poodle.SpeakThreeTimes()
	poodle.SpeakThreeTimes()
}