Events in C#

(Notes from HFC#)

Steps in Event execution
1)We need an event for event arguments

eg-> public class BallEventArgs : EventArgs

=> EventArgs is an empty class.It has no public members.Its sole purpose is to allow
your event arguments to be passed to the event handlers that use it .

2)Need to define the event in the class that'll raise it .

eg-> public event EventHandler BallInPlay

=>after EVENT keyword comes EVENTHANDLER.It is needed to tell object subscribing to event that
their event handlers need to take 2 parameters,an object named SENDER and an EVENTARGS reference names e,
and have no return value(void).

3)The subscribing classes need EventHandler methods

eg-> void ball_BallInPlay(object sender,EventArgs e )

=>Standard Naming Convention for EventHandlers -> NameOfObjectReference,followed by UNDERSCORE ,followed by
NameOfEvent.

4)Each individual object subscribes to the event

eg-> ball.BallInPlay += new EventHandler(ball_BallInPlay)

=>The += EVENT tells C# subscribe an event handler to an event.

5)A Ball Object raises its event to notify subscribers that it's in play

ex- if (BallInPlay !=null) BallInPlay(this,e)

Note: If you raise an event with no handlers ,it'll throw an exception.