simple object pool

main.cpp

#include <memory>
#include <vector>
#include <functional>
#include <iostream>

template <class T>
class SimpleObjectPool
{
public:
    using DeleterType = std::function<void(T*)>;

    void add(std::unique_ptr<T> t)
    {
        pool_.push_back(std::move(t));
    }

    std::shared_ptr<T> get()
    {
        if (pool_.empty())
        {
            throw std::logic_error("no more object");
        }

        auto pin = std::unique_ptr<T>(std::move(pool_.back()));
        pool_.pop_back();

        return std::shared_ptr<T>(pin.release(), [this](T* t)   
        {  
            pool_.push_back(std::unique_ptr<T>(t));  
        }); 
    }

    bool empty() const
    {
        return pool_.empty();
    }

    size_t size() const
    {
        return pool_.size();
    }

private:
    std::vector<std::unique_ptr<T>> pool_;
};

struct A
{
    A(){ std::cout << "A ctor" << std::endl; }
    ~A(){ std::cout << "A dtor" << std::endl; }
};
//test code
void test_object_pool()
{
    SimpleObjectPool<A> p;
    p.add(std::unique_ptr<A>(new A()));
    p.add(std::unique_ptr<A>(new A()));
    {
        auto t = p.get();
        p.get();
    }

    {
        p.get();
        p.get();
    }

    std::cout << p.size() << std::endl;
}

int main()
{
    test_object_pool();
    return 0;
}