Add Expression tree based factory for OAPH

reactiveui · Sep 26, 2010 · 6bc0d04 · 6bc0d04
1 parent 1c22a7d
commit 6bc0d04
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Showing 3 changed files with 29 additions and 16 deletions.
diff --git a/ReactiveXaml.Sample/AddPersonDialog.xaml.cs b/ReactiveXaml.Sample/AddPersonDialog.xaml.cs
@@ -185,6 +185,7 @@ protected void setupCommands()
             results.Subscribe(s => Person.Image = new BitmapImage(new Uri(s)),
                 ex => this.Log().Error("Oh no!", ex));
 
+
             /* COOLSTUFF: The Reactive Extensions
              *
              * Reactive Extensions (Rx) allow us to take existing IObservables
@@ -198,9 +199,9 @@ protected void setupCommands()
              * that we change a property since it's a ReactiveObservableObject.
              */
 
-            _SpinnerVisibility = new ObservableAsPropertyHelper<Visibility>(
+            _SpinnerVisibility = this.ObservableToProperty(
                 SetImageViaFlickr.CanExecuteObservable.Select(x => x ? Visibility.Collapsed : Visibility.Visible),
-                _ => RaisePropertyChanged("SpinnerVisibility"), Visibility.Collapsed);
+                x => x.SpinnerVisibility);
 
             OkCommand = new ReactiveCommand(
                 SetImageViaFlickr.CanExecuteObservable.CombineLatest(Person.Select(x => Person.IsValid()),

diff --git a/ReactiveXaml.Sample/App.xaml.cs b/ReactiveXaml.Sample/App.xaml.cs
@@ -88,11 +88,6 @@ public AppViewModel()
             setupCommands();
         }
 
-
-        /*
-         * Dependency Properties
-         */
-
         PersonEntry _SelectedPerson;
         public PersonEntry SelectedPerson {
             get { return _SelectedPerson; }
@@ -120,14 +115,11 @@ public AppViewModel()
          * with the host application.
          */
 
-        // FIXME: This syntax sucks, is there any way to hide it?
-        ReactiveCommand _AddPerson;
         [Export("AddPerson", typeof(IReactiveCommand))]
-        public ReactiveCommand AddPerson { get { return _AddPerson; } }
+        public ReactiveCommand AddPerson { get; protected set; }
 
-        ReactiveCommand _RemovePerson;
         [Export("RemovePerson", typeof(IReactiveCommand))]
-        public ReactiveCommand RemovePerson { get { return _RemovePerson; } }
+        public ReactiveCommand RemovePerson { get; protected set; }
 
 
         /* COOLSTUFF: Setting up Commands
@@ -150,7 +142,7 @@ public AppViewModel()
 
         protected void setupCommands()
         {
-            _AddPerson = new ReactiveCommand(item => {
+            AddPerson = new ReactiveCommand(item => {
                 var to_add = (item as PersonEntry) ?? addPersonDialog.Prompt(this, null);
 
                 if (to_add == null)
@@ -162,7 +154,7 @@ protected void setupCommands()
                 People.Add(to_add);
             });
 
-            _RemovePerson = new ReactiveCommand(param => (param ?? SelectedPerson) != null && People.Count > 0, item => {
+            RemovePerson = new ReactiveCommand(param => (param ?? SelectedPerson) != null && People.Count > 0, item => {
                 var to_remove = (PersonEntry)item ?? SelectedPerson;
                 this.Log().DebugFormat("Removing '{0}'", to_remove.Name);
                 People.Remove(to_remove);

diff --git a/ReactiveXaml/ObservableAsPropertyHelper.cs b/ReactiveXaml/ObservableAsPropertyHelper.cs
@@ -5,6 +5,7 @@
 using System.Concurrency;
 using System.Windows.Threading;
 using System.Diagnostics.Contracts;
+using System.Linq.Expressions;
 
 namespace ReactiveXaml
 {
@@ -21,8 +22,8 @@ public ObservableAsPropertyHelper(IObservable<T> observable, Action<T> on_change
             scheduler = scheduler ?? RxApp.DeferredScheduler;
             lastValue = initial_value;
 
-            observable.ObserveOn(scheduler)
-                      .DistinctUntilChanged()
+            observable.DistinctUntilChanged()
+                      .ObserveOn(scheduler)
                       .Subscribe(x => {
                 this.Log().DebugFormat("Property helper {0:X} changed", this.GetHashCode());
                 lastValue = x;
@@ -40,4 +41,23 @@ public ObservableAsPropertyHelper(IObservable<T> observable, Action<T> on_change
             }
         }
     }
+
+    public static class OAPHCreationHelperMixin
+    {
+        public static ObservableAsPropertyHelper<TRet> ObservableToProperty<TObj, TRet>(
+            this TObj This,
+            IObservable<TRet> Observable,
+            Expression<Func<TObj, TRet>> Property,
+            TRet InitialValue = default(TRet),
+            IScheduler Scheduler = null)
+            where TObj : ReactiveObject
+        {
+            Contract.Requires(This != null);
+            Contract.Requires(Observable != null);
+            Contract.Requires(Property != null);
+
+            string prop_name = RxApp.expressionToPropertyName(Property);
+            return new ObservableAsPropertyHelper<TRet>(Observable, _ => This.RaisePropertyChanged(prop_name), InitialValue, Scheduler);
+        }
+    }
 }