== Actions ==
Definition
<code csharp>
Action<int> example1 =
   (int x) => Console.WriteLine("Write {0}", x);
Action<int, int> example2 =
   (x, y) => Console.WriteLine("Write {0} and {1}", x, y);
Action example3 =  
   () => Console.WriteLine("Done");
</code>

== Using Actions to Communicate Between Background Worker and Main Threads ==

<code csharp>
using System.Windows.Threading;  // in WindowsBase.dll

public partial class MyWindow : Window
{
  public MyWindow()
  {
    InitializeComponent();
    new Thread (Work).Start();
  }
 
  void Work()
  {
    Thread.Sleep (5000);           // Simulate time-consuming task
    UpdateMessage ("The answer");
  }
 
  void UpdateMessage (string message)
  {
    Action action = () => txtMessage.Text = message;
    Dispatcher.Invoke (action);
  }
}
</code>

Source: 
  * [[http://www.albahari.com/threading/part2.aspx#_Rich_Client_Applications|Threading (Part 2): Rich Client Applications and Thread Affinity]]

== Example ==

<code csharp>
///----------------------------------------------------------------------------------------
/// <summary>
/// Close the popup menu.
/// </summary>
///----------------------------------------------------------------------------------------
public void Close()
{
    //----------------------------------------------------------------------------
    // Deal with cross thread ownership of UI control instance
    // by invoking an action delegate. In other words, 
    // popupmnu is owned by thread that instantiated it (when Open() was called),
    // so we cannot close popmnu arbitrarily.  We need the help of
    // the owner thread's Dispatcher to execute the Close() for us.
    //----------------------------------------------------------------------------
    //Action action = () => popmnuReports.IsOpen = false;
    Action action = this.CloseDelegate();
    this.Dispatcher.BeginInvoke(action);
}

///----------------------------------------------------------------------------------------
/// <summary>
/// Close method deletegate, used by cross thread dispatcher.
/// </summary>
/// <returns></returns>
///----------------------------------------------------------------------------------------
private Action CloseDelegate()
{
    return delegate()
    {
        popmnuFitting.IsOpen = false;
        m_TimerForDisplay.Enabled = false;
    };
}
</code>
== Resources ==
  * [[http://dotnetperls.com/action|DotNetPerls: Action]]
  * [[http://msdn.microsoft.com/en-us/library/018hxwa8.aspx|MSDN: Action of Delete]]
  * [[http://stackoverflow.com/questions/371054/uses-of-action-delegate-in-c|StackOverflow: Use of Action Delete in C#]]
  * [[http://weblogs.asp.net/cschittko/archive/2008/05/14/wpf-ui-update-from-background-threads.aspx|WPF UI Update from Background Threads]]