Extension method question

Question

Why the code bellow (.NET-4, Extension method) does not leave me using Application.DoEvents();?

/// <summary>
/// Invokes in the Dispatcher an empty action.
/// An thread safe equivalent of the ancient Application.DoEvents.
/// </summary>
public static void DoEvents(this Application a)
{
    Application.Current.Dispatcher.Invoke(
        System.Windows.Threading.DispatcherPriority.Background,
        new Action(delegate { })); 
}

EDIT

updated version after SLaks remark

    public static void DoEvents(this Application a)
    {
        if (a != null)
        {
            a.Dispatcher.Invoke(
                System.Windows.Threading.DispatcherPriority.Background,
                new Action(delegate { }));
        }
    }

@mcabral: see http://stackoverflow.com/questions/4502037/where-is-the-application-doevents-in-wpf — serhio, Dec 21 '10 at 18:15

score 3 · Accepted Answer · answered Dec 21 '10 at 17:58

3

You can only call extension methods an an instance.

Thus, you would be able to write Application.Current.DoEvents(), since that's an Application instance.
However, you cannot invoke it on the type itself.

answered Dec 21 '10 at 17:58

SLaks

868,454
176
1,908
1,964

just can't make answer yet :) – serhio Dec 21 '10 at 18:01
Only by creating your own class with a similar name and making a normal static method. (eg, `MyAppliction.DoEvents()`) – SLaks Dec 21 '10 at 18:01

Extension method question

EDIT

1 Answers1