c – 回调中的std :: bind和std :: function用法

假设我们有：

class EventHandler
{
public:
    template<typename Event,typename Listener>
    bool bindEvent (const Listener& function)
    {
        if (std::is_array<Event>::value)
        {
            std::cout << "You cannot register an array as an event type" << std::endl;
            return false;
        }
        if (std::is_convertible<Listener,std::function<void (Event&)>>::value)
        {
            std::cout << "Invalid callback for this event type" << std::endl;
            return false;
        }

        listeners.insert(std::make_pair(&typeid(typename std::decay<Event>::type),[=](void* ev) { function(*static_cast<Event*>(ev)); }));
    }
private:
    // for each event type,we have a list of callbacks
    // these callbacks are of the form std::function<void (void*)>
    // because we will convert between the &event and void*
    typedef std::function <void (void*)> fun;
    std::unordered_multimap <const std::type_info*,fun> listeners;
};

// example of an event type
struct KeyboardEvent
{
    int keyCode;
};

// example of an event callback
void do_key (const KeyboardEvent &event)
{
    std::cout << "I am working" << std::endl;
}

int main (int argc,char** argv)
{
    EventHandler handler;
    handler.bindEvent<KeyboardEvent> (&do_key);   // fixed typo

    return 0;
}

问题：Listener在这部分中使用什么类型？：

template<typename Event,typename Listener>
bool bindEvent(const Listener& function)

因为在main方法中我们只调用此函数.

PS：此外,此代码在std :: is_convertible部分失败. (据我所知,因为来自habindEvent< KeyboardEvent>(& do_key)的不匹配类型;