c++11 对象池的实现

const int MaxObjectNum = 10;

    template <typename T>
    class ObjectPool
    {
        template <typename... Args>
        using Constructor = std::function<std::shared_ptr<T>(Args...)>;
    public:
        ObjectPool(void)
            : m_bNeedClear(false)
        {
        }

        virtual ~ObjectPool(void)
        {
            m_bNeedClear = true;
        }

        template <typename... Args>
        void Init(size_t num, Args&&... args)
        {
            if (num <= 0 || num > MaxObjectNum)
            {
                throw std::logic_error("object num out of range.");
            }

            auto constructName = typeid(Constructor<Args...>).name();

            for (size_t i = 0; i < num; i++)
            {
                m_object_map.emplace(constructName,
                    std::shared_ptr<T>(new T(std::forward<Args>(args)...), [constructName, this]
                    (T* t)
                {
                    if (m_bNeedClear)
                    {
                        delete t;
                    }
                    else
                    {
                        m_object_map.emplace(constructName, std::shared_ptr<T>(t));
                    }
                }));
            }
        }

        template <typename... Args>
        std::shared_ptr<T> Get()
        {
            string constructName = typeid(Constructor<Args...>).name();

            auto range = m_object_map.equal_range(constructName);

            for (auto it = range.first; it != range.second; ++it)
            {
                auto ptr = it->second;
                m_object_map.erase(it);
                return ptr;
            }

            return nullptr;
        }


    private:
        std::multimap<std::string, std::shared_ptr<T> > m_object_map;
        bool m_bNeedClear;

    };

testmain.cpp

class BigObject
{
public:
    BigObject(){}

    BigObject(int a){}

    BigObject(const int& a, const int& b)
    {

    }

    void Print(const string& str)
    {
        cout << str << endl;
    }

};

void Print(shared_ptr<BigObject> p, const string& str)
{
    if (p != nullptr)
    {
        p->Print(str);
    }
}

int main()
{
    ObjectPool<BigObject> pool;
    pool.Init(2);
    {
        auto p = pool.Get();
        Print(p, "p");

        auto p2 = pool.Get();
        Print(p2, "p2");
    }

    auto p = pool.Get();
    Print(p, "p");

    auto p2 = pool.Get();
    Print(p2, "p2");

    auto p3 = pool.Get();
    Print(p3, "p3");

    pool.Init(2, 1);

    auto p4 = pool.Get<int>();

    Print(p4, "p4");
    getchar();
    return 0;
}

原文链接: https://www.cnblogs.com/kaishan1990/p/5267716.html

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