C++11: function-wrapper

#include <iostream>
#include <stdexcept>
using namespace std;

template <typename Signature>
class OneTimer;

template <typename ReturnType, typename ...Args>
class OneTimer<ReturnType(Args...)> {
    bool usable;
    ReturnType(*p)(Args...);
public:
    OneTimer(ReturnType(*func)(Args...)) : p(func), usable(true) { }
    ReturnType operator()(Args ...args) {
        if (usable) {
            usable = false;
            return p(args...);
        }
        throw std::runtime_error("Poshel nahuy");
    }
};

int random() {
    return 42;
}

int main() {
    OneTimer<int()> a = random;
    for (int i = 0; i < 10; ++i) {
        try {
            std::cout << a() << std::endl;
        } catch(std::runtime_error &e) {
            std::cerr << e.what() << std::endl;
        }
    }
    return 0;
}