/* Copyright (C) Aécio Levy 
 
 * Written by Aécio Levy - 16/03/2018
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version. 

*/

#include "stdafx.h"
#include <iostream>
template <class T>
class Singleton {
protected:
	// Static member variable
	// The instace will be "stored""
	static T* mSingleton;
	Singleton() {};
	virtual ~Singleton() {};
public:
	// Avoid Copy constructor
	Singleton(const Singleton& copy) = delete;
	// Avoid Copy assingment
	Singleton& operator = (const Singleton& copy) = delete;
	// Get the instance. If it is NULL create an instance
	// Otherwise return the instance
	static T* Instance() 
	{
		if (mSingleton == nullptr)
		{
			mSingleton = new T();
		}
		return mSingleton;
	}
	static void DeleteInstance() {
		delete mSingleton;
	}
};

class Animal : public Singleton<Animal> {
public:
	void Testing() {
		std::cout << "Testing member variable" << std::endl;
	}
};


// a static member variable has to be initialized
// out of the constructor because they are not
// shared by object. They are initialized only once
Animal* Singleton<Animal>::mSingleton = nullptr;


int main()
{
	Animal* animal = Animal::Instance();
	animal->Testing();
	std::cin.get();
	Animal::DeleteInstance();
    return 0;
}