Add ToProperty overload which sets the backing field via out parameter.

ReactiveUI/ObservableAsPropertyHelper.cs

@@ -186,6 +186,36 @@ public static class OAPHCreationHelperMixin
 
             return ret;
         }
+
+        /// <summary>
+        /// Converts an Observable to an ObservableAsPropertyHelper and
+        /// automatically provides the onChanged method to raise the property
+        /// changed notification.         
+        /// </summary>
+        /// <param name="source">The ReactiveObject that has the property</param>
+        /// <param name="property">An Expression representing the property (i.e.
+        /// 'x => x.SomeProperty'</param>
+        /// <param name="initialValue">The initial value of the property.</param>
+        /// <param name="scheduler">The scheduler that the notifications will be
+        /// provided on - this should normally be a Dispatcher-based scheduler
+        /// (and is by default)</param>
+        /// <returns>An initialized ObservableAsPropertyHelper; use this as the
+        /// backing field for your property.</returns>
+        public static ObservableAsPropertyHelper<TRet> ToProperty<TObj, TRet>(
+            this IObservable<TRet> This,
+            TObj source,
+            Expression<Func<TObj, TRet>> property,
+            out ObservableAsPropertyHelper<TRet> result,
+            TRet initialValue = default(TRet),
+            IScheduler scheduler = null)
+            where TObj : ReactiveObject
+        {
+            var ret = source.ObservableToProperty(This, property, initialValue, scheduler);
+
+            result = ret;
+            return ret;
+        }
+
     }
 }