I'm trying to create control/window events similar to how they are done in C#'s Windows Forms/WPF. Each event class contains an argument type and passes that as well as a pointer to the sending object. This is all fine and dandy when using a lambda function, but when I try to add a member function to the event I get a compile error of C2276 '&': illegal operation on bound member function expression
and C2660 'Event<MouseButtonEventArgs>::add': function does not take 1 arguments
.
How would I create an event class that can take lambda functions and member functions from any class (whether or not that class is the "sender")?
Event.h
template<class Args> struct EventListener {
/* The function type to be called by the event. */
typedef function<void(ControlBaseSPtr, Args&)> ArgsFunction;
string name;
ArgsFunction function;
};
template<class Args> class Event {
/* The function type to be called by the event. */
typedef function<void(ControlBaseSPtr, Args&)> ArgsFunction;
deque<EventListener<Args>> listeners;
Event(EventDirections direction) {
this->direction = direction;
}
void add(const string& name, ArgsFunction function) {
EventListener<Args> listener = EventListener<Args>(name, function);
for (auto it = listeners.begin(); it != listeners.end(); it++) {
if (it->name == name) {
throw exception("Event::operator+= listener already exists in the event");
}
}
listeners.push_back(listener);
}
//...
};
Control.h
class ControlBase {
Event<MouseEventArgs> _eventMouseMovedGlobal;
Event<MouseButtonEventArgs> _eventMouseButtonGlobal;
ControlBase();
void onMouseMovedGlobal(ControlBaseSPtr sender, MouseEventArgs e);
};
Control.cpp
ControlBase::ControlBase() {
// Works
_eventMouseButtonGlobal.add("some name", [](ControlSPtr control, MouseButtonEventArgs e){
//...
};
// Doesn't work
_eventMouseMovedGlobal.add("some name", bind(&onMouseMovedGlobal, this, placeholders::_2))
// Doesn't work
_eventMouseMovedGlobal.add("some name", bind(&onMouseMovedGlobal, this))
}
void ControlBase::onMouseWheelGlobal(ControlBaseSPtr sender, MouseWheelEventArgs e) {
//...
}
Well, since onMouseMovedGlobal
has 2 input arguments, you need placeholders or values for both of them when creating a binder. So, instead of
_eventMouseMovedGlobal.add("some name", bind(&onMouseMovedGlobal, this, placeholders::_2))
you need
_eventMouseMovedGlobal.add("some name", bind(&ControlBase::onMouseMovedGlobal, this, placeholders::_1, placeholders::_2))