Software Engineering and Computer Games

12.2. The listeners

As we mentioned in Chapter 8: Critters, a critter uses the Strategy pattern to farm out the task of listening to its cListener *_plistener member with a call to feellistener.

void cCritter::feellistener(Real dt) 
{ 
    _plistener->listen(dt, this); 
} 

We pass the pointer this to the listener so that it can change the fields of this calling cCritter as required. Because a cListener takes a cGame * argument to its listen method, we can say that the cListener can ‘navigate’ to a cGame. The caller critter’s pgame() holds the cController object that stores all of the keys and mouse actions you need to process.

We pass a dt argument to the plistener->feellistener because the mouse-based listener cListenerCursor needs to know the