C#

<font color="#008800">//the event handler delegate</font>
public delegate void MyEventHandler(object sender, EventArgs e);
 
<font color="#008800">//the parent class</font>
Class A
{
   <font color="#008800">//the event declaration</font>
   public event MyEventHandler DataChanged;
 
<font color="#008800">   //The method that raises the event.  
   //This is the only place where the event is raised.  
   //To raise the event from the parent class, do   
   //<code>OnDataChanged(EventArgs.Empty)</code>. 
   //To raise the event from the child class, do
   //<code>base.OnDataChanged(EventArgs.Empty)</code>.</font>
   protected void OnDataChanged(EventArgs e)
   {
        if(ElementMouseUp !=null)
             ElementMouseUp(this, e);
   }
   ....
 
}