typedef typename get_result_type<T>::type result_type;

template<typename... Ts>

result_type operator()(T& f, const Ts&... args) const {

return f(std::forward<Ts>(args)...);

}

public:

rebindable_reference() : m_ptr(nullptr) { }

rebindable_reference(T& value) : m_ptr(&value) { }

template<typename U>

rebindable_reference(const rebindable_reference<U>& other) : m_ptr(other.ptr()) { }

inline bool bound() const {

return m_ptr != nullptr;

}

inline void rebind(T& value) {

m_ptr = &value;

}

template<typename U>

inline void rebind(const rebindable_reference<U>& other) {

m_ptr = other.ptr();

}

inline T* ptr() const {

CPPA_REQUIRE(bound());

return m_ptr;

}

inline T& get() const {

CPPA_REQUIRE(bound());

return *m_ptr;

}

inline operator T&() const {

CPPA_REQUIRE(bound());

return *m_ptr;

}

template<typename... Ts>

typename call_helper<T>::result_type operator()(Ts&&... args) {

call_helper<T> f;

return f(get(), std::forward<Ts>(args)...);

}

private:

T* m_ptr;