Unique pointer

• If it goes out of the scope, it will be destroyed.
• Can not copy it.
  • 만약에 복사가 됐다면, 두개가 같은걸 바라보는데, 하나가 사라지면 다 사라지니까 그 자체가 말이 안된다.

class Entity
{
	public:
	Entity()
	{ std::cout << "Created Entity!" << std::endl;}
	~Entity()
	{ std::cout << "Destroyed Entity!" << std::endl;}
	void Print(){}
};

int main()
{
	{
		std::unique_ptr<Entity> entity = std::make_unique<Entity>();
		// std::unique_ptr<Entity> e0 = entity // it doesn't work. (not unique!)
		entity->Print();
		// if it goes out of this scope ( "{}" ), then it is destroyed.
	}
}

Shared pointer

class Entity
{
	public:
	Entity()
	{ std::cout << "Created Entity!" << std::endl;}
	~Entity()
	{ std::cout << "Destroyed Entity!" << std::endl;}
	void Print(){}
};

int main()
{
	{
		std::shared_ptr<Entity> sharedEntity = std::make_shared<Entity>);
		std::shared_ptr<Entity> e0 = sharedEntity // works fine!
		entity->Print();

	}
}

Weak pointer

• if you copy the shared pointer to shared pointer, then pointer count increase
• if you copy the shared pointer to weak pointer, then pointer count doesn’t increase

class Entity
{
	public:
	Entity()
	{ std::cout << "Created Entity!" << std::endl;}
	~Entity()
	{ std::cout << "Destroyed Entity!" << std::endl;}
	void Print(){}
};

int main()
{
	{
		std::shared_ptr<Entity> sharedEntity = std::make_shared<Entity>);
		std::weak_ptr<Entity> weak_ptr = sharedEntity // works fine!
		entity->Print();

	}
}