C# formalizes the event handling by using delegate.
It uses event keyword to declare a delegate type as the event listener and all delegate instances as the handler.
The following code defines a delegate as the prototype for all event handlers.
delegate void PrinterEventHandler(string s);
It requires that all event handlers for the print events should take string as parameter.
The following code uses event keyword to make a delegate as an event.
using System;
public delegate void PrinterEventHandler(string s);
public class Printer
{
private string stringValue;
public event PrinterEventHandler printEventHandler;
public string StringValue
{
get
{
return stringValue;
}
set
{
printEventHandler(value);
stringValue = value;
}
}
}
class Test
{
static void consoleHandler(string str)
{
Console.WriteLine("console handler:" + str);
}
static void Main()
{
Printer p = new Printer();
p.printEventHandler += consoleHandler;
p.StringValue = "rntsoft.com";
}
}
The output:
console handler:rntsoft.com
event can have the following modifiers.
virtual
overridden
abstract
sealed
static