Writing your first Rx Application

did you check out the wmv high version? text is much clearer there

triggers are based on dependency properties, and you could write something that makes a dependecy property into an observable

im working on something like that infact

also @wes, Observable.Context is static, what if i want to have one observable use one context and another observable to use another?

-edit-

this discussion continued on the rx forums where a neater solution was found

-end edit-

Hello again, i wrote a little helper class for converting dependency properties to Observable, im not sure its the best way to do it though, what do you guys think? am i missing something? There are some anonymous Observable/disposable in rx that i'd liked to use but they are internal.. i suspect there is something smarter i can do with the Create methods but i coudnt get around making a helper class..

public partial class MainWindow : Window {
  public MainWindow( ) {
  InitializeComponent( );
  Observable.Context = SynchronizationContext.Current;
  this.ActualHeightAsObservable( ).Subscribe( d => label1.Content = d );
  }
}

public class DependencyObservable<T> : IDisposable {
  EventHandler eh; DependencyPropertyDescriptor des; object instance;

  public DependencyObservable( IObserver<T> observer, DependencyProperty dp, Type ownertype, object ins ) {
    des = DependencyPropertyDescriptor.FromProperty( dp, ownertype );
    instance = ins;
    eh = new EventHandler( ( o, e ) => observer.OnNext( ( T )des.GetValue( instance ) ) );
    des.AddValueChanged( instance, eh ); 
  }

  public void Dispose( ) {
    des.RemoveValueChanged( instance, eh ); 
  }
}

public static class WindowExtensions {
  public static IObservable<double> ActualHeightAsObservable( this MainWindow w ) {
    return CreateWithDisposable<double>( obs => new DependencyObservable<double>( obs, MainWindow.HeightProperty, 
      w.GetType( ), w ) )
  }
}

The nice thing is that the returned observable respects all the rules of Dependency properties, if the dp is changed by a style, trigger or binding, the Observable should reflect that (ive only tried with bindings though)