* Bug fixes

- Ordering, ThenOrdering: Error if IComparer.Compare returns a number greater than 1 or smaller than -1
- Aggregating: IsDefaulted is not set to true if source collection is null
* New features
- ICanNotifyMethodChanged and ICanNotifyPropertyChanged interfaces

src/ObservableComputations.Test/ExpressionWatcherTests.cs

@@ -94,7 +94,7 @@ public void TestRaiseValueChanged1()
 			bool raised = false;
 			Item item = new Item();
 			Expression<Func<bool>> expression = () => item.Num == "1";
-			ExpressionWatcher expressionWatcher = new ExpressionWatcher(
+			ExpressionWatcher expressionWatcher = new ExpressionWatcher(null, 
 				ExpressionWatcher.GetExpressionInfo(expression));
 			expressionWatcher.ValueChanged = (ew, sender, eventArgs) => { raised = true; };
 			item.Num = "1";
@@ -108,7 +108,7 @@ public void TestRaiseValueChanged2()
 			bool raised = false;
 			object item = new Item();
 			Expression<Func<bool>> expression = () => ((Item)item).Num == "1";
-			ExpressionWatcher expressionWatcher = new ExpressionWatcher(
+			ExpressionWatcher expressionWatcher = new ExpressionWatcher(null, 
 				ExpressionWatcher.GetExpressionInfo(expression));
 			expressionWatcher.ValueChanged = (ew, sender, eventArgs) => { raised = true; };
 			((Item)item).Num = "1";
@@ -122,7 +122,7 @@ public void TestRaiseValueChanged3()
 			bool raised = false;
 			Item item = new Item();
 			Expression<Func<string>> expression = () => (string)item.NumObject;
-			ExpressionWatcher expressionWatcher = new ExpressionWatcher(
+			ExpressionWatcher expressionWatcher = new ExpressionWatcher(null, 
 				ExpressionWatcher.GetExpressionInfo(expression));
 			expressionWatcher.ValueChanged = (ew, sender, eventArgs) => { raised = true; };
 			item.Num = "1";
@@ -137,7 +137,7 @@ public void TestRaiseValueChanged4()
 			Item item = new Item();
 			item.Num = "777";
 			Expression<Func<string>> expression = () => item.GetChild(item.AltNum).Num;
-			ExpressionWatcher expressionWatcher = new ExpressionWatcher(
+			ExpressionWatcher expressionWatcher = new ExpressionWatcher(null, 
 				ExpressionWatcher.GetExpressionInfo(expression));
 			expressionWatcher.ValueChanged = (ew, sender, eventArgs) => { raised = true; };
 			item.Num = "1";
@@ -156,7 +156,7 @@ public void TestRaiseValueChanged41()
 			item.Num = "777";
 			item.GetChild(item.AltNum).SetChild("888", new Item());
 			Expression<Func<string>> expression = () => item.GetChild(item.AltNum).GetChild("888").Num;
-			ExpressionWatcher expressionWatcher = new ExpressionWatcher(
+			ExpressionWatcher expressionWatcher = new ExpressionWatcher(null, 
 				ExpressionWatcher.GetExpressionInfo(expression));
 			expressionWatcher.ValueChanged = (ew, sender, eventArgs) => { raised = true; };
 			item.Num = "1";
@@ -176,7 +176,7 @@ public void TestRaiseValueChanged5()
 			item.Num = "777";
 			Expression<Func<string, string>> expression = n => item.GetChild(item.AltNum + n).Num;
 			object[] parameters = new object[]{"777"};
-			ExpressionWatcher expressionWatcher = new ExpressionWatcher(
+			ExpressionWatcher expressionWatcher = new ExpressionWatcher(null, 
 				ExpressionWatcher.GetExpressionInfo(expression), parameters);
 			expressionWatcher.ParameterValues.SequenceEqual(parameters);
 			expressionWatcher.ValueChanged = (ew, sender, eventArgs) => { raised = true; };
@@ -194,7 +194,7 @@ public void TestRaiseValueChanged6()
 			bool raised = false;
 			Item item = new Item();
 			Expression<Func<string>> expression = () => (item.Num == "777" ? item.GetChild("888") : item.GetChild("000")).Num;
-			ExpressionWatcher expressionWatcher = new ExpressionWatcher(
+			ExpressionWatcher expressionWatcher = new ExpressionWatcher(null, 
 				ExpressionWatcher.GetExpressionInfo(expression));
 			expressionWatcher.ValueChanged = (ew, sender, eventArgs) => { raised = true; };
 			item.Num = "777";
@@ -209,7 +209,7 @@ public void TestRaiseValueChanged61()
 			Item item = new Item();
 			item.Num = "777";
 			Expression<Func<string>> expression = () => (item.Num == "777" ? item.GetChild("888") : item.GetChild("000")).Num;
-			ExpressionWatcher expressionWatcher = new ExpressionWatcher(
+			ExpressionWatcher expressionWatcher = new ExpressionWatcher(null, 
 				ExpressionWatcher.GetExpressionInfo(expression));
 			expressionWatcher.ValueChanged = (ew, sender, eventArgs) => { raised = true; };
 			item.GetChild("888").Num = "888";
@@ -224,7 +224,7 @@ public void TestRaiseValueChanged63()
 			Item item = new Item();
 			item.Num = "777";
 			Expression<Func<int, string>> expression = n => (item.Num == "777" ? item.GetChild("888" + n) : item.GetChild("000")).Num;
-			ExpressionWatcher expressionWatcher = new ExpressionWatcher(
+			ExpressionWatcher expressionWatcher = new ExpressionWatcher(null, 
 				ExpressionWatcher.GetExpressionInfo(expression), new object[]{1});
 			expressionWatcher.ValueChanged = (ew, sender, eventArgs) => { raised = true; };
 			item.GetChild("888" + 1).Num = "888";
@@ -239,7 +239,7 @@ public void TestRaiseValueChanged64()
 			Item item = new Item();
 			item.Num = "777" + 1;
 			Expression<Func<int, string>> expression = n => (item.Num == "777" + n ? item.GetChild("888") : item.GetChild("000")).Num;
-			ExpressionWatcher expressionWatcher = new ExpressionWatcher(
+			ExpressionWatcher expressionWatcher = new ExpressionWatcher(null, 
 				ExpressionWatcher.GetExpressionInfo(expression), new object[]{1});
 			expressionWatcher.ValueChanged = (ew, sender, eventArgs) => { raised = true; };
 			item.GetChild("888").Num = "888";
@@ -254,7 +254,7 @@ public void TestRaiseValueChanged7()
 			bool raised = false;
 			Item item = new Item();
 			Expression<Func<string>> expression = () => item.GetChild("777").Num;
-			ExpressionWatcher expressionWatcher = new ExpressionWatcher(
+			ExpressionWatcher expressionWatcher = new ExpressionWatcher(null, 
 				ExpressionWatcher.GetExpressionInfo(expression));
 			expressionWatcher.ValueChanged = (ew, sender, eventArgs) => { raised = true; };
 			item.SetChild("777", new Item(){Num = "888"});
@@ -269,7 +269,7 @@ public void TestRaiseValueChanged8()
 			bool raised = false;
 			Item item = new Item();
 			Expression<Func<Item, string>> expression = i => i.GetChild(i.Num == "777" ? "888" : "999").Num;
-			ExpressionWatcher expressionWatcher = new ExpressionWatcher(
+			ExpressionWatcher expressionWatcher = new ExpressionWatcher(null, 
 				ExpressionWatcher.GetExpressionInfo(expression), new object[] {item});
 			expressionWatcher.ValueChanged = (ew, sender, eventArgs) => { raised = true; };
 			item.SetChild("000", new Item(){Num = "000"});
@@ -293,7 +293,7 @@ public void TestRaiseValueChanged9()
 			bool raised = false;
 			Item item = new Item();
 			Expression<Func<Item, string>> expression = i => i.GetChild("777").Num + i.GetChild("999").Num;
-			ExpressionWatcher expressionWatcher = new ExpressionWatcher(
+			ExpressionWatcher expressionWatcher = new ExpressionWatcher(null, 
 				ExpressionWatcher.GetExpressionInfo(expression), new object[]{item});
 			expressionWatcher.ValueChanged = (ew, sender, eventArgs) => { raised = true; };
 			item.SetChild("777", new Item(){Num = "888"});
@@ -312,7 +312,7 @@ public void TestRaiseValueChanged10()
 			Item item1 = new Item();
 			Item item2 = new Item();
 			Expression<Func<Item, Item, string>> expression = (i1, i2) => i1.GetChild("777").Num + i2.GetChild("999").Num;
-			ExpressionWatcher expressionWatcher = new ExpressionWatcher(
+			ExpressionWatcher expressionWatcher = new ExpressionWatcher(null, 
 				ExpressionWatcher.GetExpressionInfo(expression), new object[]{item1, item2});
 			expressionWatcher.ValueChanged = (ew, sender, eventArgs) => { raised = true; };
 			item1.SetChild("777", new Item(){Num = "888"});
@@ -330,7 +330,7 @@ public void TestRaiseValueChanged11()
 			bool raised = false;
 			object item = new Item();
 			Expression<Func<object, string>> expression = i => ((Item) i).GetChild("777").Num + ((Item) i).GetChild("999").Num;
-			ExpressionWatcher expressionWatcher = new ExpressionWatcher(
+			ExpressionWatcher expressionWatcher = new ExpressionWatcher(null, 
 				ExpressionWatcher.GetExpressionInfo(expression), new object[]{item});
 			expressionWatcher.ValueChanged = (ew, sender, eventArgs) => { raised = true; };
 			((Item)item).SetChild("777", new Item(){Num = "888"});
@@ -349,7 +349,7 @@ public void TestRaiseValueChanged12()
 			Item item1 = new Item();
 			Item item2 = new Item();
 			Expression<Func<string>> expression = () => item1.GetChild("777").Num + item2.GetChild("999").Num;
-			ExpressionWatcher expressionWatcher = new ExpressionWatcher(
+			ExpressionWatcher expressionWatcher = new ExpressionWatcher(null, 
 				ExpressionWatcher.GetExpressionInfo(expression));
 			expressionWatcher.ValueChanged = (ew, sender, eventArgs) => { raised = true; };
 			item1.SetChild("777", new Item(){Num = "888"});
@@ -369,7 +369,7 @@ public void TestRaiseValueChanged13()
 			Item item2 = new Item();
 			item1.Child = item2;
 			Expression<Func<string>> expression = () => item1.Child.Num;
-			ExpressionWatcher expressionWatcher = new ExpressionWatcher(
+			ExpressionWatcher expressionWatcher = new ExpressionWatcher(null, 
 				ExpressionWatcher.GetExpressionInfo(expression));
 			expressionWatcher.ValueChanged = (ew, sender, eventArgs) => { raised = true; };
 			item1.Child = new Item();

src/ObservableComputations/Collections/ThenOrdering.cs

@@ -774,7 +774,7 @@ private int getOrderedIndex(TOrderingValue orderingValue, int lowerIndex, int up
 
 				TOrderingValue middleItemOrderingValue = _orderingValues[middleIndex];
 
-				int comparisonWithMiddleItem = _comparer.Compare(orderingValue, middleItemOrderingValue);
+				int comparisonWithMiddleItem =  Math.Sign(_comparer.Compare(orderingValue, middleItemOrderingValue));
 
 				if (comparisonWithMiddleItem == 0)
 				{

src/ObservableComputations/Common/ExpressionWatcher.cs

@@ -12,6 +12,7 @@ namespace ObservableComputations
 {
 	internal sealed class ExpressionWatcher
 	{
+		IComputing _owner;
 		internal Position _position;
 		internal readonly PropertyChangedEventSubscription[] _propertyChangedEventSubscriptions;
 		internal readonly MethodChangedEventSubscription[] _methodChangedEventSubscriptions;
@@ -318,8 +319,9 @@ private void initialize(ExpressionInfo expressionInfo)
 			if (expressionInfo._constantCallTrees != null) workWithCallTrees(expressionInfo._constantCallTrees);
 		}
 
-		internal ExpressionWatcher(ExpressionInfo expressionInfo)
+		internal ExpressionWatcher(IComputing owner, ExpressionInfo expressionInfo)
 		{
+			_owner = owner;
 			ExpressionToWatch = expressionInfo._expressionToWatch;
 			_parameterValues = null;
 			_propertyChangedEventSubscriptions = new PropertyChangedEventSubscription[expressionInfo._callCount];
@@ -348,8 +350,9 @@ private ExpressionWatcher(object[] parameterValues, ExpressionInfo expressionInf
 			initialize(expressionInfo);
 		}
 
-		public ExpressionWatcher(ExpressionInfo expressionInfo, object[] parameters)
+		public ExpressionWatcher(IComputing owner, ExpressionInfo expressionInfo, object[] parameters)
 		{
+			_owner = owner;
 			ExpressionToWatch = expressionInfo._expressionToWatch;
 			_parameterValues = parameters;
 			_propertyChangedEventSubscriptions = new PropertyChangedEventSubscription[expressionInfo._callCount];
@@ -735,16 +738,18 @@ private void workWithCallTreeNode(CallTreeNode node, object holder, WorkWithCall
 					_currentComputings[callIndex] = newComputingInternal;
 				}
 
+
+				string memberName = node._call.Name;
 				switch (node._call.Type)
 				{
 					case CallType.PropertyOrField:
+
 
-						if (node._holder is INotifyPropertyChanged notifyPropertyChanged)
+						void subscribePropertyChanged(INotifyPropertyChanged notifyPropertyChanged)
 						{
-							string propertyName = node._call.Name;
 							node._propertyChangedEventHandler = (sender, args) =>
 							{
-								if (!_disposed && args.PropertyName == propertyName)
+								if (!_disposed && args.PropertyName == memberName)
 #if DEBUG
 									processChange(node, root, sender, args);
 #else
@@ -753,21 +758,34 @@ private void workWithCallTreeNode(CallTreeNode node, object holder, WorkWithCall
 							};
 
 							notifyPropertyChanged.PropertyChanged += node._propertyChangedEventHandler;
-							_propertyChangedEventSubscriptions[callIndex] = new PropertyChangedEventSubscription(notifyPropertyChanged, node._propertyChangedEventHandler);
+							_propertyChangedEventSubscriptions[callIndex] =
+								new PropertyChangedEventSubscription(notifyPropertyChanged, node._propertyChangedEventHandler);
+						}
+
+
+						if (node._holder is ICanNotifyPropertyChanged canNotifyPropertyChanged)
+						{
+							if (canNotifyPropertyChanged.CanNotifyPropertyChanged(memberName, _rootExpressionWatcher._owner))
+								subscribePropertyChanged(canNotifyPropertyChanged);
+						}
+						else if (node._holder is INotifyPropertyChanged notifyPropertyChanged)
+						{
+							subscribePropertyChanged(notifyPropertyChanged);
 						}
 						break;
 					case CallType.Method:
-						if (node._holder is INotifyMethodChanged notifyMethodChanged)
+						int argumentsCount = node._call.GetArgumentValues.Length;
+
+						void subscribeMethodChanged(INotifyMethodChanged notifyMethodChanged)
 						{
-							CallTreeNode nodeCopy = node;
 							node._methodChangedEventHandler = (sender, args) =>
 							{
-								if (!_disposed && args.MethodName == nodeCopy._call.Name)
+								if (!_disposed && args.MethodName == memberName)
 								{
-									int length = nodeCopy._call.GetArgumentValues.Length;
-									object[] argumentValues = new object[length];
-									for (int index = 0; index < length; index++)
-										argumentValues[index] = nodeCopy._call.GetArgumentValues[index].DynamicInvoke(_parameterValues);
+
+									object[] argumentValues = new object[argumentsCount];
+									for (int index = 0; index < argumentsCount; index++)
+										argumentValues[index] = node._call.GetArgumentValues[index].DynamicInvoke(_parameterValues);
 
 									if (args.ArgumentsPredicate(argumentValues))
 #if DEBUG
@@ -776,11 +794,21 @@ private void workWithCallTreeNode(CallTreeNode node, object holder, WorkWithCall
 										processChange(node, sender, args);
 #endif
 								}
-
 							};
-			
+
 							notifyMethodChanged.MethodChanged += node._methodChangedEventHandler;
-							_methodChangedEventSubscriptions[callIndex] = new MethodChangedEventSubscription(notifyMethodChanged, node._methodChangedEventHandler);
+							_methodChangedEventSubscriptions[callIndex] =
+								new MethodChangedEventSubscription(notifyMethodChanged, node._methodChangedEventHandler);
+						}
+
+						if (node._holder is ICanNotifyMethodChanged canNotifyMethodChanged)
+						{
+							if (canNotifyMethodChanged.CanNotifyMethodChanged(memberName, argumentsCount, _rootExpressionWatcher._owner))
+								subscribeMethodChanged(canNotifyMethodChanged);
+						}
+						else if (node._holder is INotifyMethodChanged notifyMethodChanged)
+						{
+							subscribeMethodChanged(notifyMethodChanged);
 						}
 
 						ExpressionWatcher[] nodeCallArguments = node._callArguments;

src/ObservableComputations/Common/Interface/ICanNotifyMethodChanged.cs

@@ -0,0 +1,9 @@
+using System.ComponentModel;
+
+namespace ObservableComputations
+{
+	public interface ICanNotifyMethodChanged : INotifyMethodChanged
+	{
+		bool CanNotifyMethodChanged(string methodName, int argumentsCount, IComputing computing);
+	}
+}

src/ObservableComputations/Common/Interface/ICanNotifyPropertyChanged.cs

@@ -0,0 +1,9 @@
+using System.ComponentModel;
+
+namespace ObservableComputations
+{
+	public interface ICanNotifyPropertyChanged : INotifyPropertyChanged
+	{
+		bool CanNotifyPropertyChanged(string propertyName, IComputing computing);
+	}
+}

src/ObservableComputations/Common/Interface/ISourceIndexerPropertyTracker.cs

@@ -13,12 +13,12 @@ internal interface ISourceIndexerPropertyTracker
 
 	internal interface ILeftSourceIndexerPropertyTracker : ISourceIndexerPropertyTracker
 	{
-		void HandleSourcePropertyChanged(object sender, PropertyChangedEventArgs propertyChangedEventArgs);
+		new void HandleSourcePropertyChanged(object sender, PropertyChangedEventArgs propertyChangedEventArgs);
 	}
 
 	internal interface IRightSourceIndexerPropertyTracker : ISourceIndexerPropertyTracker
 	{
-		void HandleSourcePropertyChanged(object sender, PropertyChangedEventArgs propertyChangedEventArgs);
+		new void HandleSourcePropertyChanged(object sender, PropertyChangedEventArgs propertyChangedEventArgs);
 	}
 
 

src/ObservableComputations/Common/Interface/ISourceItemChangeProcessor.cs

@@ -11,11 +11,11 @@ internal interface ISourceItemChangeProcessor : IComputingInternal
 
 	internal interface ISourceItemKeyChangeProcessor : ISourceItemChangeProcessor
 	{
-		void ProcessSourceItemChange(ExpressionWatcher expressionWatcher);
+		new void ProcessSourceItemChange(ExpressionWatcher expressionWatcher);
 	}
 
 	internal interface ISourceItemValueChangeProcessor : ISourceItemChangeProcessor
 	{
-		void ProcessSourceItemChange(ExpressionWatcher expressionWatcher);
+		new void ProcessSourceItemChange(ExpressionWatcher expressionWatcher);
 	}
 }

src/ObservableComputations/Common/Utils.cs

@@ -614,7 +614,7 @@ internal static void getItemInfoContent<TExpression, TExpressionCompiled>(object
 		{
 			if (!expressionContainsParametrizedLiveLinqCalls)
 			{
-				watcher = new ExpressionWatcher(valueSelectorExpressionInfo, sourceItems);
+				watcher = new ExpressionWatcher(current, valueSelectorExpressionInfo, sourceItems);
 				func = default(TExpressionCompiled);
 				nestedComputings = null;
 				expressionCallCount = valueSelectorExpressionInfo._callCount;
@@ -638,7 +638,7 @@ internal static void getItemInfoContent<TExpression, TExpressionCompiled>(object
 
 				ExpressionWatcher.ExpressionInfo expressionInfo =
 					ExpressionWatcher.GetExpressionInfo(predicateExpression);
-				watcher = new ExpressionWatcher(expressionInfo);
+				watcher = new ExpressionWatcher(current, expressionInfo);
 
 				expressionCallCount = expressionInfo._callCount;
 			}

src/ObservableComputations/ObservableComputations.csproj

@@ -19,18 +19,17 @@
     <NeutralLanguage>en</NeutralLanguage>
     <GeneratePackageOnBuild>true</GeneratePackageOnBuild>
     <PackageRequireLicenseAcceptance>false</PackageRequireLicenseAcceptance>
-    <PackageReleaseNotes>* New features
-- specifying a default value for the all scalar operators (reduces verbosity)
-- CollectionItemProcessing (reduces verbosity)
-
-* Renamed
-— CollectionProcessing -&gt; CollectionItemsProcessing</PackageReleaseNotes>
+    <PackageReleaseNotes>* Bug fixes
+- Ordering, ThenOrdering: Error if IComparer.Compare returns a number greater than 1 or smaller than -1
+- Aggregating: IsDefaulted is not set to true if source collection is null
+* New features
+- ICanNotifyMethodChanged and ICanNotifyPropertyChanged interfaces</PackageReleaseNotes>
     <Version>2.2.0</Version>
     <AssemblyName>ObservableComputations</AssemblyName>
     <PackageId>ObservableComputations</PackageId>
     <Product>ObservableComputations</Product>
-    <AssemblyVersion>2.2.0.0</AssemblyVersion>
-    <FileVersion>2.2.0.0</FileVersion>
+    <AssemblyVersion>2.2.1.0</AssemblyVersion>
+    <FileVersion>2.2.1.0</FileVersion>
     <PackageIconUrl></PackageIconUrl>
     <PackageLicenseFile>LICENSE</PackageLicenseFile>
     <Copyright>Igor Buchelnikov (c)</Copyright>