Understanding Events in C#

Question

I'm very new to programming, but I'm pretty sure I've almost got this Events thing down. I just need a few pointers, I guess. I'm trying to create a simple example of an Event, one that simply says "Hello!" every second or so. First I have my "Publisher" class:

 public class Publisher
{
     public delegate void MyEventHandler();
     public event MyEventHandler MyEvent;
     public void MyMethod()
    {
       while (true) { Thread.Sleep(1000); if (MyEvent != null) { MyEvent(); } }
    }
}

Next, I have my "Subscriber" class:

 public class Subscriber
{
     public void Subscribe(Publisher TheObject)
    {
         TheObject.MyEvent += new Publisher.MyEventHandler(SayHello);
    }
     public void SayHello() { Console.WriteLine("Hello!"); }
}

Finally, in my Program:

 public class Program {
 static void Main(string[] args) {     

 var ThePublisher = new Publisher();
 var TheSubscriber = new Subscriber();
 TheSubscriber.Subscribe(ThePublisher);
 ThePublisher.MyEvent();

 }
 }

The compiler says that I have an error though. It put a red line underneath "MyEvent" in "ThePublisher.MyEvent();" in Program. The error says "The event 'NameOfProject.Publisher.MyEvent' can only appear on the left hand side of += or -= (except when used from within the type 'NameOfProject.Publisher')" However, I know that I put in "+=" and nothing else. It is stated in my Subscriber class. What am I missing? What am I doing wrong?

Answer 1

In the last line, you're calling ThePublisher.MyEvent() instead of ThePublisher.MyMethod() , as you probably intended to do.

You may not trigger an event directly from outside the class which defines the event.