???

template <int N, typename T>
class bucket_sketch
{
public:

    bucket_sketch()
        :storage_n(0)
    {
        for (int i = 0; i < N; i++)
        {
            storage[i] = 0;
        }
    }

public:

    T storage[N];
    int storage_n;

public:

    void* set(T value)
    {
        storage[storage_n] = value;

        return &storage[storage_n++];
    }

    T get(void* address)
    {
        for (int i = 0; i < storage_n; i++)
        {
            if (address == (void*)&storage[i]) return storage[i];
        }
        return T();
    }
};

template <int N, typename T, typename... Ts>
class bucket :public bucket_sketch<N, T>, public bucket_sketch<N, Ts>...
{
public:

    bucket()
        :element_n(N), current(0), bucket_sketch<N, T>(), bucket_sketch<N, Ts>()...
    {
        for (int i = 0; i < N; i++)
        {
            element[i] = 0;
        }
    }

private:

    int element_n;
    int current;

    void* element[N];

public:

    template <typename U>
    U set(int n, U value)
    {
        typename element[n] = bucket_sketch<N, U>::set(value);

        return value;
    }

    template <typename U>
    U get(int n)
    {
        return typename bucket_sketch<N, U>::get(element[n]);
    }

public:

    template <typename U>
    operator U()
    {
        return this->get<U>(this->current);
    }

    typename bucket<N, T, Ts...>& operator[] (int elem)
    {
        current = elem;
        return *this;
    }

    template <typename U>
    U operator= (U value)
    {
        return this->set<U>(current, value);
    }

};