EventSystem

A simple event system where classes can subscribe to events and respond to them.

Required Files

This solution includes the Event System, and some example usage files. If you want to use the Event System, you only need the following files...

• EventSystem.h
• EventSystem.cpp
• Listener.h
• Event.h

Initializing

The event system itself does not need any special initialization. However, the objects that LISTEN for events must subscribe to those events. Example...

// Subscribe batman to the Bat Signal event  
Batman batman;  
EventSystem::Instance()->RegisterClient("BAT_SIGNAL", &batman);  

Sending Events

Anyone with access to the EventSystem can send events by using the SendEvent() method. The first parameter is what event you are sending, and the second parameter is a void* that you can use to send parameters with.

// Send an event
EventSystem::Instance()->SendEvent("BAT_SIGNAL", 1);

Processing Events

Every frame of your program, you should call the Event Systems ProcessEvents() method. This method goes through all events currently in queue and has their listeners respond to those events. So once this method has finished, there will be 0 events left over in the queue. Example...

// Process events that have occurred this frame  
EventSystem::Instance()->ProcessEvents();  

Unsubscribing a listener from ALL events

You can unsubscribe a listener from all events by calling UnregisterAll(Listener*) method. Example...

// Unsubscribe Batman from any future events. He quits.  
EventSystem::Instance()->UnregisterAll(&batman);  

Unsubscribing a listener from CERTAIN events

You can unsubscribe a listener from specific events by calling UnregisterClient(EVENTID, Listener*) method. Example...

// Batman no longer cares about Bank Robberies. Stop listening for them.. 
EventSystem::Instance()->UnregisterClient("BANK_ROBBERY", &batman);  

Clearing Events

If you need to get rid of all events currently in queue (for some reason), you can do so with the ClearEvents() method. Example...

// Clear Events  
EventSystem::Instance()->ClearEvents();  

Shutting down the system

When you are finished with the Event System, you can shut it down by calling Shutdown() method. Example...

// Shutting down the Event System  
EventSystem::Instance()->Shutdown();