// The ThreadWithState class contains the information needed for
// a task, the method that executes the task, and a delegate
// to call when the task is complete.
//
public class ThreadWithState {
// State information used in the task.
private string boilerplate;
private int value;
// Delegate used to execute the callback method when the
// task is complete.
private ExampleCallback callback;
// The constructor obtains the state information and the
// callback delegate.
public ThreadWithState(string text, int number,
ExampleCallback callbackDelegate)
{
boilerplate = text;
value = number;
callback = callbackDelegate;
}
// The thread procedure performs the task, such as
// formatting and printing a document, and then invokes
// the callback delegate with the number of lines printed.
public void ThreadProc()
{
Console.WriteLine(boilerplate, value);
if (callback != null)
callback(1);
}
}
// Delegate that defines the signature for the callback method.
//
public delegate void ExampleCallback(int lineCount);
// Entry point for the example.
//
public class Example
{
public static void Main()
{
// Supply the state information required by the task.
ThreadWithState tws = new ThreadWithState(
"This report displays the number {0}.",
42,
new ExampleCallback(ResultCallback)
);
Thread t = new Thread(new ThreadStart(tws.ThreadProc));
t.Start();
Console.WriteLine("Main thread does some work, then waits.");
t.Join();
Console.WriteLine(
"Independent task has completed; main thread ends.");
}
// The callback method must match the signature of the
// callback delegate.
//
public static void ResultCallback(int lineCount)
{
Console.WriteLine(
"Independent task printed {0} lines.", lineCount);
}
}