how about universal reference for variadic template parameters

[mumbi]

template <typename... U> void operator()(U && ...u) { if (slot_state::connected() && !slot_state::blocked()) { call_slot(std::forward<U>(u)...); } }

protected: void call_slot(Args ...args) override { func(args...); }

operator() uses universal reference for variadic template parameters.

but call_slot protected function does not.

so we should do not use universal reference for signal wrapper.

how do you think about this?