object_pool.cpp

#include <iostream>
#include <array>

class Particle
{
public:
    Particle() : m_frameLeft(0) {}

    void init(double x, double y, int lifeTime)
    {
        m_x = x;
        m_y = y;
        m_frameLeft = lifeTime;
    }

    bool inUse() const
    {
        return m_frameLeft > 0;
    }

    void animate()
    {
        if (!inUse())
        {
            return;
        }

        m_frameLeft--;
        m_x += 1.0;
        m_y += 1.0;
    }

private:
    int m_frameLeft;
    double m_x;
    double m_y;
};

class ParticlePool
{
public:
    void create(double x, double y, int lifeTime)
    {
        for (auto &particle : m_particles)
        {
            if (!particle.inUse())
            {
                particle.init(x, y, lifeTime);
                return;
            }
        }
    }

    void animate()
    {
        for (auto &particle : m_particles)
        {
            particle.animate();
        }
    }

    void showMemory()
    {
        std::cout << "|";
        for (auto &particle : m_particles)
        {
            if (particle.inUse())
            {
                std::cout << "*";
            }
            else
            {
                std::cout << " ";
            }
        }
        std::cout << "|" << std::endl;
    }

private:
    static const int POOL_SIZE = 25;
    std::array<Particle, POOL_SIZE> m_particles;
};

int main()
{
    ParticlePool pool;
    while (true)
    {
        pool.create(0, 0, 25);
        pool.animate();
        pool.showMemory();
    }
}