delegate void PrintItemHandler(string message); //The kind of function we need
private static void DoWork(string[] data, PrintItemHandler func = null)
{
foreach (string item in data)
{
if (func == null)
{
//Default behavior
Console.WriteLine("Default: " + item);
}
else
{
func(item); //Invoking the delegate, just like a function
}
}
}
static void Main(string[] args)
{
var data = new string[] { "Name 1", "Name 2", "Name 3", "nane 4" };
Console.WriteLine("Version 1 - Manual Delegate");
PrintItemHandler handler = new PrintItemHandler(PrintToScreen);
DoWork(data, handler);
Console.WriteLine();
Console.WriteLine("Version 2 - Implied Delegate");
DoWork(data, PrintToScreen);
Console.WriteLine();
Console.WriteLine("Version 3 - Multicast Delegate");
PrintItemHandler handler2 = new PrintItemHandler(PrintToScreen);
handler2 += PrintToDebugger;
handler2 += PrintToLogFile;
DoWork(data, handler2);
//What if we could build function "on the fly"
//instead of external ones
//Anonymous Function (least important, ugliest syntax)
PrintItemHandler handler3 = delegate(string msg) {
Console.WriteLine(msg);
};
//Labmda Expression
PrintItemHandler handler4 = msg => Console.WriteLine(msg);
}
