Go-OOP

oop.go

package main

import (
	"fmt"
	"reflect"
)

// Animal base "class".
type Animal struct {
	Name string
	mean bool
}

// AnimalSounder interface exposes MakeNoise() method, which provides the different Animal "sounds".
type AnimalSounder interface {
	MakeNoise()
}

// Dog is a type of Animal.
type Dog struct {
	Animal
	BarkStrength int
}

// Cat is a type of Animal.
type Cat struct {
	Basics       Animal
	MeowStrength int
}

// Lion is a type of Animal.
type Lion struct {
	Basics       Animal
	RoarStrength int
}

// MakeNoise (*Dog) barks.
func (animal *Dog) MakeNoise() {
	animalType := reflect.ValueOf(animal).Type().Elem().Name()
	animal.PerformNoise(animal.BarkStrength, "BARK", animalType)
}

// MakeNoise (*Cat) meows.
func (animal *Cat) MakeNoise() {
	animalType := reflect.ValueOf(animal).Type().Elem().Name()
	animal.Basics.PerformNoise(animal.MeowStrength, "MEOW", animalType)
}

// MakeNoise (*Lion) roars.
func (animal *Lion) MakeNoise() {
	animalType := reflect.ValueOf(animal).Type().Elem().Name()
	animal.Basics.PerformNoise(animal.RoarStrength, "ROAR!!  ", animalType)
}

// MakeSomeNoise exposes AnimalSounder's MakeNoise() method.
func MakeSomeNoise(animalSounder AnimalSounder) {
	animalSounder.MakeNoise()
}

func main() {
	myDog := &Dog{
		Animal{
			Name: "Rover", // Name
			mean: false,   // mean
		},
		2, // BarkStrength
	}

	myCat := &Cat{
		Basics: Animal{
			Name: "Julius",
			mean: true,
		},
		MeowStrength: 3,
	}

	wildLion := &Lion{
		Basics: Animal{
			Name: "Aslan",
			mean: true,
		},
		RoarStrength: 5,
	}

	MakeSomeNoise(myDog)
	MakeSomeNoise(myCat)
	MakeSomeNoise(wildLion)
}

// PerformNoise is a generic method shared by all implementations of Animal.
func (animal *Animal) PerformNoise(strength int, sound string, animalType string) {
	if animal.mean == true {
		strength = strength * 5
	}

	fmt.Printf("%s (%s): \n", animal.Name, animalType)

	for voice := 0; voice < strength; voice++ {
		fmt.Printf("%s ", sound)
	}

	fmt.Println("\n")
}