Merge pull request #2224 from mrcarlberg/kvo_honor_options_when_creating_change_dictionary

KVO now honor options when creating change dictionary

AppKit/CPKeyValueBinding.j

@@ -156,7 +156,7 @@ var CPBindingOperationAnd = 0,
 
         [self _updatePlaceholdersWithOptions:options forBinding:aName];
 
-        [aDestination addObserver:self forKeyPath:aKeyPath options:CPKeyValueObservingOptionNew context:aBinding];
+        [aDestination addObserver:self forKeyPath:aKeyPath options:0 context:aBinding];
 
         var bindings = [bindingsMap objectForKey:[_source UID]];
 

Foundation/CPKeyValueObserving.j

@@ -327,6 +327,7 @@ var kvoNewAndOld        = CPKeyValueObservingOptionNew | CPKeyValueObservingOpti
     Class           _nativeClass;
     CPDictionary    _changesForKey;
     CPDictionary    _nestingForKey;
+    CPDictionary    _minOptionsForKey;
     Object          _observersForKey;
     int             _observersForKeyLength;
     CPSet           _replacedKeys;
@@ -354,6 +355,7 @@ var kvoNewAndOld        = CPKeyValueObservingOptionNew | CPKeyValueObservingOpti
         _observersForKey    = {};
         _changesForKey      = {};
         _nestingForKey      = {};
+        _minOptionsForKey   = {};
         _observersForKeyLength = 0;
 
         [self _replaceClass];
@@ -767,12 +769,20 @@ var kvoNewAndOld        = CPKeyValueObservingOptionNew | CPKeyValueObservingOpti
 
     if (options & CPKeyValueObservingOptionInitial)
     {
-        var newValue = [_targetObject valueForKeyPath:aPath];
+        var changes;
 
-        if (newValue === nil || newValue === undefined)
-            newValue = [CPNull null];
+        if (options & CPKeyValueObservingOptionNew)
+        {
+            var newValue = [_targetObject valueForKeyPath:aPath];
+
+            if (newValue == nil)
+                newValue = [CPNull null];
+
+            changes = @{ CPKeyValueChangeKindKey: CPKeyValueChangeSetting, CPKeyValueChangeNewKey: newValue };
+        } else {
+            changes = @{ CPKeyValueChangeKindKey: CPKeyValueChangeSetting };
+        }
 
-        var changes = @{ CPKeyValueChangeNewKey: newValue };
         [anObserver observeValueForKeyPath:aPath ofObject:_targetObject change:changes context:aContext];
     }
 }
@@ -819,7 +829,9 @@ var kvoNewAndOld        = CPKeyValueObservingOptionNew | CPKeyValueObservingOpti
 
 - (void)_sendNotificationsForKey:(CPString)aKey changeOptions:(CPDictionary)changeOptions isBefore:(BOOL)isBefore
 {
-    var changes = _changesForKey[aKey];
+    var changes = _changesForKey[aKey],
+        observers = [_observersForKey[aKey] allValues],
+        observersMinimumOptions = 0;
 
     if (isBefore)
     {
@@ -838,61 +850,78 @@ var kvoNewAndOld        = CPKeyValueObservingOptionNew | CPKeyValueObservingOpti
 
         _nestingForKey[aKey] = 1;
 
+        // Get the combined minimum of the ...Old and ...New options for all observers
+        var count = observers ? observers.length : 0;
+
+        while (count--)
+        {
+            var observerInfo = observers[count];
+
+            observersMinimumOptions |= observerInfo.options & kvoNewAndOld;
+        }
+
+        _minOptionsForKey[aKey] = observersMinimumOptions;
         changes = changeOptions;
 
-        var indexes = [changes objectForKey:CPKeyValueChangeIndexesKey],
-            setMutationKind = changes[_CPKeyValueChangeSetMutationKindKey];
-
-        if (setMutationKind)
+        if (observersMinimumOptions & CPKeyValueObservingOptionOld)
         {
-            var setMutationObjects = [changes[_CPKeyValueChangeSetMutationObjectsKey] copy],
-                setExistingObjects = [[_targetObject valueForKey: aKey] copy];
+            var indexes = [changes objectForKey:CPKeyValueChangeIndexesKey],
+                setMutationKind = changes[_CPKeyValueChangeSetMutationKindKey];
 
-            if (setMutationKind == CPKeyValueMinusSetMutation)
+            if (setMutationKind)
             {
-                [setExistingObjects intersectSet: setMutationObjects];
-                [changes setValue:setExistingObjects forKey:CPKeyValueChangeOldKey];
+                var setMutationObjects = [changes[_CPKeyValueChangeSetMutationObjectsKey] copy],
+                    setExistingObjects = [[_targetObject valueForKey: aKey] copy];
+
+                if (setMutationKind == CPKeyValueMinusSetMutation)
+                {
+                    [setExistingObjects intersectSet: setMutationObjects];
+                    [changes setValue:setExistingObjects forKey:CPKeyValueChangeOldKey];
+                }
+                else if (setMutationKind === CPKeyValueIntersectSetMutation || setMutationKind === CPKeyValueSetSetMutation)
+                {
+                    [setExistingObjects minusSet: setMutationObjects];
+                    [changes setValue:setExistingObjects forKey:CPKeyValueChangeOldKey];
+                }
+
+                //for unordered to-many relationships (CPSet) even new values can only be calculated before!!!
+                if (setMutationKind === CPKeyValueUnionSetMutation || setMutationKind === CPKeyValueSetSetMutation)
+                {
+                    [setMutationObjects minusSet: setExistingObjects];
+                    //hide new value (for CPKeyValueObservingOptionPrior messages)
+                    //as long as "didChangeValue..." is not yet called!
+                    changes[_CPKeyValueChangeSetMutationNewValueKey] = setMutationObjects;
+                }
             }
-            else if (setMutationKind === CPKeyValueIntersectSetMutation || setMutationKind === CPKeyValueSetSetMutation)
+            else if (indexes)
             {
-                [setExistingObjects minusSet: setMutationObjects];
-                [changes setValue:setExistingObjects forKey:CPKeyValueChangeOldKey];
+                var type = [changes objectForKey:CPKeyValueChangeKindKey];
+
+                // for ordered to-many relationships, oldvalue is only sensible for replace and remove
+                if (type === CPKeyValueChangeReplacement || type === CPKeyValueChangeRemoval)
+                {
+                    //FIXME: do we need to go through and replace "" with CPNull?
+                    var newValues = [[_targetObject mutableArrayValueForKeyPath:aKey] objectsAtIndexes:indexes];
+                    [changes setValue:newValues forKey:CPKeyValueChangeOldKey];
+                }
+            }
+            else
+            {
+                var oldValue = [_targetObject valueForKey:aKey];
+
+                if (oldValue === nil || oldValue === undefined)
+                    oldValue = [CPNull null];
+
+                [changes setObject:oldValue forKey:CPKeyValueChangeOldKey];
             }
 
-            //for unordered to-many relationships (CPSet) even new values can only be calculated before!!!
-            if (setMutationKind === CPKeyValueUnionSetMutation || setMutationKind === CPKeyValueSetSetMutation)
-            {
-                [setMutationObjects minusSet: setExistingObjects];
-                //hide new value (for CPKeyValueObservingOptionPrior messages)
-                //as long as "didChangeValue..." is not yet called!
-                changes[_CPKeyValueChangeSetMutationNewValueKey] = setMutationObjects;
-            }
-        }
-        else if (indexes)
-        {
-            var type = [changes objectForKey:CPKeyValueChangeKindKey];
-
-            // for ordered to-many relationships, oldvalue is only sensible for replace and remove
-            if (type === CPKeyValueChangeReplacement || type === CPKeyValueChangeRemoval)
-            {
-                //FIXME: do we need to go through and replace "" with CPNull?
-                var newValues = [[_targetObject mutableArrayValueForKeyPath:aKey] objectsAtIndexes:indexes];
-                [changes setValue:newValues forKey:CPKeyValueChangeOldKey];
-            }
-        }
-        else
-        {
-            var oldValue = [_targetObject valueForKey:aKey];
-
-            if (oldValue === nil || oldValue === undefined)
-                oldValue = [CPNull null];
-
-            [changes setObject:oldValue forKey:CPKeyValueChangeOldKey];
         }
 
         [changes setObject:1 forKey:CPKeyValueChangeNotificationIsPriorKey];
-
         _changesForKey[aKey] = changes;
+
+        // Clear ...New option as it should never be sent for a ...Prior option
+        observersMinimumOptions &= ~CPKeyValueObservingOptionNew;
     }
     else
     {
@@ -927,55 +956,97 @@ var kvoNewAndOld        = CPKeyValueObservingOptionNew | CPKeyValueObservingOpti
 
         [changes removeObjectForKey:CPKeyValueChangeNotificationIsPriorKey];
 
-        var indexes = [changes objectForKey:CPKeyValueChangeIndexesKey],
-            setMutationKind = changes[_CPKeyValueChangeSetMutationKindKey];
+        observersMinimumOptions = _minOptionsForKey[aKey];
 
-        if (setMutationKind)
+        if (observersMinimumOptions & CPKeyValueObservingOptionNew)
         {
-            //old and new values for unordered to-many relationships can only be calculated before
-            //set recalculated hidden new value as soon as "didChangeValue..." is called!
-            var newValue = changes[_CPKeyValueChangeSetMutationNewValueKey];
-            [changes setValue:newValue forKey:CPKeyValueChangeNewKey];
+            var indexes = [changes objectForKey:CPKeyValueChangeIndexesKey],
+                setMutationKind = changes[_CPKeyValueChangeSetMutationKindKey];
 
-            //delete hidden values
-            delete changes[_CPKeyValueChangeSetMutationNewValueKey];
-            delete changes[_CPKeyValueChangeSetMutationObjectsKey];
-            delete changes[_CPKeyValueChangeSetMutationKindKey];
-        }
-        else if (indexes)
-        {
-            var type = [changes objectForKey:CPKeyValueChangeKindKey];
-
-            // for ordered to-many relationships, newvalue is only sensible for replace and insert
-            if (type == CPKeyValueChangeReplacement || type == CPKeyValueChangeInsertion)
+            if (setMutationKind)
             {
-                //FIXME: do we need to go through and replace "" with CPNull?
-                var newValues = [[_targetObject mutableArrayValueForKeyPath:aKey] objectsAtIndexes:indexes];
-                [changes setValue:newValues forKey:CPKeyValueChangeNewKey];
+                //old and new values for unordered to-many relationships can only be calculated before
+                //set recalculated hidden new value as soon as "didChangeValue..." is called!
+                var newValue = changes[_CPKeyValueChangeSetMutationNewValueKey];
+                [changes setValue:newValue forKey:CPKeyValueChangeNewKey];
+
+                //delete hidden values
+                delete changes[_CPKeyValueChangeSetMutationNewValueKey];
+                delete changes[_CPKeyValueChangeSetMutationObjectsKey];
+                delete changes[_CPKeyValueChangeSetMutationKindKey];
+            }
+            else if (indexes)
+            {
+                var type = [changes objectForKey:CPKeyValueChangeKindKey];
+
+                // for ordered to-many relationships, newvalue is only sensible for replace and insert
+                if (type == CPKeyValueChangeReplacement || type == CPKeyValueChangeInsertion)
+                {
+                    //FIXME: do we need to go through and replace "" with CPNull?
+                    var newValues = [[_targetObject mutableArrayValueForKeyPath:aKey] objectsAtIndexes:indexes];
+                    [changes setValue:newValues forKey:CPKeyValueChangeNewKey];
+                }
+            }
+            else
+            {
+                var newValue = [_targetObject valueForKey:aKey];
+
+                if (newValue === nil || newValue === undefined)
+                    newValue = [CPNull null];
+
+                [changes setObject:newValue forKey:CPKeyValueChangeNewKey];
+            }
+        }
+
+        delete _minOptionsForKey[aKey];
+        delete _changesForKey[aKey];
+    }
+
+    var count = observers ? observers.length : 0,
+        changesCache = {};
+
+    while (count--)
+    {
+        var observerInfo = observers[count],
+            options = observerInfo.options,
+            onlyNewAndOldOptions = options & kvoNewAndOld,
+            observerChanges = nil;
+
+        if (isBefore)
+        {
+            // Only send 'observeValueForKeyPath:' for '...Prior' option when handling 'willChangeValue...'
+            if (options & CPKeyValueObservingOptionPrior)
+            {
+                observerChanges = changes;
+                // The new values are not yet created in the change dictionary so remove ...New option to get a working cache below
+                onlyNewAndOldOptions &= ~CPKeyValueObservingOptionNew;
             }
         }
         else
         {
-            var newValue = [_targetObject valueForKey:aKey];
-
-            if (newValue === nil || newValue === undefined)
-                newValue = [CPNull null];
-
-            [changes setObject:newValue forKey:CPKeyValueChangeNewKey];
+            observerChanges = changes;
         }
 
-        delete _changesForKey[aKey];
-    }
-
-    var observers = [_observersForKey[aKey] allValues],
-        count = observers ? observers.length : 0;
-
-    while (count--)
-    {
-        var observerInfo = observers[count];
-
-        if (!isBefore || (observerInfo.options & CPKeyValueObservingOptionPrior))
-            [observerInfo.observer observeValueForKeyPath:aKey ofObject:_targetObject change:changes context:observerInfo.context];
+        if (observerChanges)
+        {
+            // Don't change the 'change' dictionary when the observer wants the minimum options.
+            // The ...New option is remved above for the ...Prior case
+            if (onlyNewAndOldOptions !== observersMinimumOptions)
+            {
+                // Use a subset of the 'change' dictionary. First try to find it in the cache
+                observerChanges = changesCache[onlyNewAndOldOptions];
+                if (!observerChanges)
+                {
+                    // Not in the cache. Build a new dictionary and store it in the cache
+                    changesCache[onlyNewAndOldOptions] = observerChanges = [changes mutableCopy];
+                    if (!(onlyNewAndOldOptions & CPKeyValueObservingOptionOld))
+                        [observerChanges removeObjectForKey:CPKeyValueChangeOldKey];
+                    if (!(onlyNewAndOldOptions & CPKeyValueObservingOptionNew))
+                        [observerChanges removeObjectForKey:CPKeyValueChangeNewKey];
+                }
+            }
+            [observerInfo.observer observeValueForKeyPath:aKey ofObject:_targetObject change:observerChanges context:observerInfo.context];
+        }
     }
 
     var dependentKeysMap = _nativeClass[DependentKeysKey];
@@ -1226,13 +1297,21 @@ var kvoNewAndOld        = CPKeyValueObservingOptionNew | CPKeyValueObservingOpti
 {
     if (aKeyPath === _firstPart)
     {
-        var oldValue = [_value valueForKeyPath:_secondPart],
-            newValue = [_object valueForKeyPath:_firstPart + "." + _secondPart],
-            pathChanges = @{
-                    CPKeyValueChangeNewKey: newValue ? newValue : [CPNull null],
-                    CPKeyValueChangeOldKey: oldValue ? oldValue : [CPNull null],
-                    CPKeyValueChangeKindKey: CPKeyValueChangeSetting,
-                };
+        var pathChanges = [CPMutableDictionary dictionaryWithObject:CPKeyValueChangeSetting forKey:CPKeyValueChangeKindKey];
+
+        if (_options & CPKeyValueObservingOptionOld)
+        {
+            var oldValue = [_value valueForKeyPath:_secondPart];
+
+            [pathChanges setObject:oldValue != null ? oldValue : [CPNull null] forKey:CPKeyValueChangeOldKey];
+        }
+
+        if (_options & CPKeyValueObservingOptionNew)
+        {
+            var newValue = [_object valueForKeyPath:_firstPart + "." + _secondPart];
+
+            [pathChanges setObject:newValue != null ? newValue : [CPNull null] forKey:CPKeyValueChangeNewKey];
+        }
 
         [_observer observeValueForKeyPath:_firstPart + "." + _secondPart ofObject:_object change:pathChanges context:_context];
 

Tests/AppKit/CPArrayControllerTest.j

@@ -10,6 +10,9 @@
 
     CPArray             observations;
     int                 aCount @accessors;
+
+    CPArray             nameValues @accessors;
+    CPArray             depValues @accessors;
 }
 
 - (CPArray)makeTestArray
@@ -19,6 +22,22 @@
         [Employee employeeWithName:@"Tom" department:[Department departmentWithName:@"CommonJS"]]];
 }
 
+- (CPArray)makeTestArrayMany
+{
+    var a = [[Employee employeeWithName:@"Francisco" department:[Department departmentWithName:@"Cappuccino"]],
+        [Employee employeeWithName:@"Ross" department:[Department departmentWithName:@"Cappuccino"]],
+        [Employee employeeWithName:@"Tom" department:[Department departmentWithName:@"CommonJS"]]];
+
+    var i = 10000;
+
+    while (i--)
+    {
+        [a addObject:[Employee employeeWithName:@"Martin" + i department:[Department departmentWithName:@"Magic Lightning"]]];
+    }
+
+    return a;
+}
+
 - (void)initControllerWithSimpleArray
 {
     // Copy the array to allow the original to be reused.
@@ -1054,6 +1073,54 @@
     [self assert:[1, 2, 3] equals:[arrayController1 arrangedObjects] message:"normal selection"];
 }
 
+/*!
+    Test that bindings are not generation any change dictionary with Old or New values as a observer
+*/
+- (void)testCreationOfOldAndNeChangeDictionaryinObserverProtocol
+{
+    [self initControllerWithContentBinding];
+
+    var arrayController = [self arrayController];
+
+    [self bind:@"nameValues" toObject:arrayController withKeyPath:@"arrangedObjects.name" options:nil];
+
+    countGetName = 0;
+
+    [self setItemsArray:[]];
+    [self assert:0 equals:countGetName];
+
+    countGetName = 0;
+
+    [self setItemsArray:[self makeTestArray]];
+    [self assert:3 equals:countGetName message:@"3 items in array and one '.name' bindings should make 3 accesses to the name property not " + countGetName + " times"];
+}
+
+/*!
+    Test the speed of set an big array when the old was an empty.
+    Also test the speed when an empty array is set and the old is an big
+*/
+- (void)testPerformance
+{
+    [self initControllerWithContentBinding];
+
+    var arrayController = [self arrayController];
+    [self bind:@"nameValues" toObject:arrayController withKeyPath:@"arrangedObjects.name" options:nil];
+    [self bind:@"depValues" toObject:arrayController withKeyPath:@"arrangedObjects.department" options:nil];
+
+    [self setItemsArray:[]];
+    var bigArray = [self makeTestArrayMany];
+
+    var d = new Date();
+    [self setItemsArray:bigArray];
+    var dd = new Date();
+    [self setItemsArray:[]];
+    var ddd = new Date();
+
+    CPLog.warn("\n" + [self className] + " Performance tests");
+    CPLog.warn("EmptyArray -> BigArray (" + [bigArray count] + "): " + (dd - d) + "ms.");
+    CPLog.warn("BigArray (" + [bigArray count] + ") -> EmptyArray: " + (ddd - dd) + "ms.");
+}
+
 - (void)observeValueForKeyPath:keyPath
     ofObject:anActivity
     change:change
@@ -1099,8 +1166,20 @@
     [_contentArray replaceObjectAtIndex:index withObject:anObject];
 }
 
+- (void)setItemsArray:(CPArray)newValue
+{
+    [self setValue:newValue forKey:@"contentArray"];
+}
+
+- (CPArray)itemsArray
+{
+    return [self valueForKey:@"contentArray"];
+}
+
 @end
 
+var countGetName;
+
 @implementation Employee : CPObject
 {
     CPString            _name @accessors(property=name);
@@ -1128,6 +1207,12 @@
     return [CPString stringWithFormat:@"<Employee %@>", [self name]];
 }
 
+- (CPString)name
+{
+    countGetName++;
+    return _name;
+}
+
 @end
 
 @implementation Department : CPObject

Tests/Foundation/CPKVOTest.j

@@ -29,7 +29,7 @@
 {
     bob = [[PersonTester alloc] init];
 
-    [bob addObserver:self forKeyPath:@"name" options:nil context:@"testAddObserver"];
+    [bob addObserver:self forKeyPath:@"name" options:CPKeyValueObservingOptionNew | CPKeyValueObservingOptionOld context:@"testAddObserver"];
 
     [bob setValue:@"bob" forKey:@"name"];
 
@@ -42,7 +42,7 @@
 {
     bob = [[PersonTester alloc] init];
 
-    [bob addObserver:self forKeyPath:@"name" options:nil context:@"testUnobservedKey"];
+    [bob addObserver:self forKeyPath:@"name" options:0 context:@"testUnobservedKey"];
 
     [bob setValue:@"555" forKey:@"phoneNumber"];
 
@@ -54,8 +54,8 @@
 {
     bob = [[PersonTester alloc] init];
 
-    [bob addObserver:self forKeyPath:@"name" options:nil context:@"testAddTwoObservers"];
-    [bob addObserver:[CPObject new] forKeyPath:@"name" options:nil context:@"testAddTwoObservers"];
+    [bob addObserver:self forKeyPath:@"name" options:CPKeyValueObservingOptionNew | CPKeyValueObservingOptionOld context:@"testAddTwoObservers"];
+    [bob addObserver:[CPObject new] forKeyPath:@"name" options:CPKeyValueObservingOptionNew | CPKeyValueObservingOptionOld context:@"testAddTwoObservers"];
 
     [bob setValue:@"bob" forKey:@"name"];
 
@@ -68,7 +68,7 @@
 {
     bob = [[PersonTester alloc] init];
 
-    [bob addObserver:self forKeyPath:@"phoneNumber" options:nil context:@"testDirectIVarObservation"];
+    [bob addObserver:self forKeyPath:@"phoneNumber" options:CPKeyValueObservingOptionNew | CPKeyValueObservingOptionOld context:@"testDirectIVarObservation"];
 
     [bob setValue:@"555" forKey:@"phoneNumber"];
 
@@ -81,8 +81,8 @@
 {
     bob = [[PersonTester alloc] init];
 
-    [bob addObserver:self forKeyPath:@"name" options:nil context:@"testRemoveObserver"];
-    [bob addObserver:[CPString new] forKeyPath:@"name" options:nil context:@"testRemoveObserver"];
+    [bob addObserver:self forKeyPath:@"name" options:0 context:@"testRemoveObserver"];
+    [bob addObserver:[CPString new] forKeyPath:@"name" options:0 context:@"testRemoveObserver"];
 
     [bob removeObserver:self forKeyPath:@"name"];
 
@@ -96,8 +96,8 @@
     bob = [[PersonTester alloc] init];
     obj = [CPString new];
 
-    [bob addObserver:self forKeyPath:@"name" options:nil context:@"testRemoveOtherObserver"];
-    [bob addObserver:obj forKeyPath:@"name" options:nil context:@"testRemoveOtherObserver"];
+    [bob addObserver:self forKeyPath:@"name" options:CPKeyValueObservingOptionNew | CPKeyValueObservingOptionOld context:@"testRemoveOtherObserver"];
+    [bob addObserver:obj forKeyPath:@"name" options:CPKeyValueObservingOptionNew | CPKeyValueObservingOptionOld context:@"testRemoveOtherObserver"];
 
     [bob removeObserver:obj forKeyPath:@"name"];
 
@@ -113,8 +113,8 @@
     obj = [CPArray new];
     obj2 = [CPString new];
 
-    [bob addObserver:obj forKeyPath:@"name" options:nil context:@"testRemoveAllObservers"];
-    [bob addObserver:obj2 forKeyPath:@"name" options:nil context:@"testRemoveAllObservers"];
+    [bob addObserver:obj forKeyPath:@"name" options:0 context:@"testRemoveAllObservers"];
+    [bob addObserver:obj2 forKeyPath:@"name" options:0 context:@"testRemoveAllObservers"];
 
     [bob removeObserver:obj forKeyPath:@"name"];
     [bob removeObserver:obj2 forKeyPath:@"name"];
@@ -133,7 +133,7 @@
 
     [dict addObserver:self
            forKeyPath:@"dictionaryKey"
-             options:nil
+             options:CPKeyValueObservingOptionNew | CPKeyValueObservingOptionOld
              context:@"testDictionary"];
 
     [dict setObject:@"Jo Bob Ray" forKey:@"dictionaryKey"];
@@ -147,7 +147,20 @@
 
     bob = [[PersonTester alloc] init];
 
-    [bob addObserver:self forKeyPath:@"name" options:CPKeyValueObservingOptionPrior context:@"testPriorObservationOption"];
+    [bob addObserver:self forKeyPath:@"name" options:CPKeyValueObservingOptionPrior | CPKeyValueObservingOptionNew | CPKeyValueObservingOptionOld context:@"testPriorObservationOption"];
+
+    [bob setValue:@"bob" forKey:@"name"];
+
+    [self assertTrue:_sawPriorObservation message:@"asked for CPKeyValueObservingOptionPrior but did not recieve corresponding notification"];
+}
+
+- (void)testPriorObservationOptionNoOld
+{
+    _sawPriorObservation = NO;
+
+    bob = [[PersonTester alloc] init];
+
+    [bob addObserver:self forKeyPath:@"name" options:CPKeyValueObservingOptionPrior | CPKeyValueObservingOptionNew context:@"testPriorObservationOptionNoOld"];
 
     [bob setValue:@"bob" forKey:@"name"];
 
@@ -162,7 +175,23 @@
 
     bob.name = "paul";
 
-    [bob addObserver:self forKeyPath:@"name" options:CPKeyValueObservingOptionInitial context:@"testInitialObservationOption"];
+    [bob addObserver:self forKeyPath:@"name" options:CPKeyValueObservingOptionInitial | CPKeyValueObservingOptionNew context:@"testInitialObservationOption"];
+    [bob removeObserver:self forKeyPath:@"name"];
+
+    [bob setValue:@"bob" forKey:@"name"];
+
+    [self assertTrue:_sawInitialObservation message:@"asked for CPKeyValueObservingOptionInitial but did not recieve corresponding notification"];
+}
+
+- (void)testInitialObservationOptionNoNew
+{
+    _sawInitialObservation = NO;
+
+    bob = [[PersonTester alloc] init];
+
+    bob.name = "paul";
+
+    [bob addObserver:self forKeyPath:@"name" options:CPKeyValueObservingOptionInitial context:@"testInitialObservationOptionNoNew"];
     [bob removeObserver:self forKeyPath:@"name"];
 
     [bob setValue:@"bob" forKey:@"name"];
@@ -178,8 +207,8 @@
 
     bob.name = "paul";
 
-    [bob addObserver:self forKeyPath:@"bobName" options:0 context:@"testDependentKeyObservation"];
-    [bob addObserver:self forKeyPath:@"twiceRemoved" options:0 context:@"testDependentKeyObservation2"];
+    [bob addObserver:self forKeyPath:@"bobName" options:CPKeyValueObservingOptionOld context:@"testDependentKeyObservation"];
+    [bob addObserver:self forKeyPath:@"twiceRemoved" options:CPKeyValueObservingOptionOld context:@"testDependentKeyObservation2"];
 
     [bob setValue:@"bob" forKey:@"name"];
 
@@ -194,7 +223,7 @@
 
     [cs101 setTeacher:bob];
 
-    [cs101 addObserver:self forKeyPath:@"teacher.name" options:0 context:@"testMultipartKey"];
+    [cs101 addObserver:self forKeyPath:@"teacher.name" options:CPKeyValueObservingOptionNew context:@"testMultipartKey"];
 
     [bob setName:@"bob"];
 
@@ -209,7 +238,7 @@
 
     [bob setValue:focus forKey:@"car"];
 
-    [bob addObserver:self forKeyPath:@"self.car.thisCar.model" options:0 context:@"testMultiPartKeysWhereValuesEvaluateToSelf"];
+    [bob addObserver:self forKeyPath:@"self.car.thisCar.model" options:CPKeyValueObservingOptionNew context:@"testMultiPartKeysWhereValuesEvaluateToSelf"];
 
     [focus setValue:@"ford focus" forKey:@"model"];
 
@@ -225,7 +254,7 @@
     [cs101 setTeacher:bob];
     [bob setValue:focus forKey:@"car"];
 
-    [cs101 addObserver:self forKeyPath:@"teacher.car.model" options:0 context:@"testThreePartKey"];
+    [cs101 addObserver:self forKeyPath:@"teacher.car.model" options:CPKeyValueObservingOptionNew context:@"testThreePartKey"];
 
     [focus setValue:@"ford focus" forKey:@"model"];
     [self assertTrue: _sawObservation message:@"Never recieved an observation"];
@@ -240,7 +269,7 @@
     [cs101 setTeacher:bob];
     [focus setValue:@"2000" forKey:@"year"];
 
-    [cs101 addObserver:self forKeyPath:@"teacher.car.year" options:0 context:@"testThreePartKeyPart2"];
+    [cs101 addObserver:self forKeyPath:@"teacher.car.year" options:CPKeyValueObservingOptionNew context:@"testThreePartKeyPart2"];
 
     [bob setValue:focus forKey:@"car"];
 
@@ -290,7 +319,7 @@
     [a setValue:[E new] forKeyPath:@"b.c.d.e"];
     [a setValue:[F new] forKeyPath:@"b.c.d.e.f"];
 
-    [a addObserver:self forKeyPath:@"b.c.d.e.f" options:0 context:@"testCrazyKeyPathChanges"];
+    [a addObserver:self forKeyPath:@"b.c.d.e.f" options:CPKeyValueObservingOptionNew context:@"testCrazyKeyPathChanges"];
 
     var newD = [D new];
 
@@ -311,7 +340,7 @@
     [a setValue:[E new] forKeyPath:@"b.c.d.e"];
     [a setValue:[F new] forKeyPath:@"b.c.d.e.f"];
 
-    [a addObserver:self forKeyPath:@"b.c.d.e.f" options:0 context:@"testCrazyKeyPathChanges2"];
+    [a addObserver:self forKeyPath:@"b.c.d.e.f" options:CPKeyValueObservingOptionNew context:@"testCrazyKeyPathChanges2"];
 
     [a setValue:nil forKeyPath:@"b.c"];
 
@@ -328,7 +357,7 @@
     [a setValue:[E new] forKeyPath:@"b.c.d.e"];
     [a setValue:[F new] forKeyPath:@"b.c.d.e.f"];
 
-    [a addObserver:self forKeyPath:@"b.c.d.e.f" options:0 context:@"testCrazyKeyPathChanges3"];
+    [a addObserver:self forKeyPath:@"b.c.d.e.f" options:CPKeyValueObservingOptionNew context:@"testCrazyKeyPathChanges3"];
 
     [a setValue:7 forKeyPath:@"b.c.d.e.f"];
 
@@ -341,7 +370,7 @@
 
     [tester setValue:[1, 2, 3, 4] forKey:@"managedObjects"];
 
-    [tester addObserver:self forKeyPath:@"managedObjects" options:0 context:@"testInsertIntoToManyProperty"];
+    [tester addObserver:self forKeyPath:@"managedObjects" options:CPKeyValueObservingOptionNew context:@"testInsertIntoToManyProperty"];
 
     [tester insertObject:5 inManagedObjectsAtIndex:4];
 
@@ -354,7 +383,7 @@
 
     [tester setValue:[1, 2, 3, 4] forKey:@"managedObjects"];
 
-    [tester addObserver:self forKeyPath:@"managedObjects" options:0 context:@"testRemoveFromToManyProperty"];
+    [tester addObserver:self forKeyPath:@"managedObjects" options:CPKeyValueObservingOptionOld context:@"testRemoveFromToManyProperty"];
 
     [tester removeObjectFromManagedObjectsAtIndex:0];
 
@@ -367,7 +396,7 @@
 
     tester.tester = [ToManyTester new];
     [tester.tester setValue:[1, 2, 3, 4] forKey:@"managedObjects"];
-    [tester addObserver:self forKeyPath:@"tester.managedObjects" options:0 context:@"testInsertIntoToManyPropertyIndirectly"];
+    [tester addObserver:self forKeyPath:@"tester.managedObjects" options:CPKeyValueObservingOptionNew context:@"testInsertIntoToManyPropertyIndirectly"];
 
     [tester.tester insertObject:5 inManagedObjectsAtIndex:4];
 
@@ -381,7 +410,7 @@
     tester.tester = [ToManyTester new];
 
     [tester.tester setValue:[1, 2, 3, 4] forKey:@"subviews"];
-    [tester addObserver:self forKeyPath:@"tester.subviews" options:0 context:@"testInsertIntoArrayPropertyIndirectly"];
+    [tester addObserver:self forKeyPath:@"tester.subviews" options:CPKeyValueObservingOptionNew context:@"testInsertIntoArrayPropertyIndirectly"];
 
     [tester.tester insertSubview:5 atIndex:4];
 
@@ -395,7 +424,7 @@
     tester.tester = [ToManyTester new];
 
     [tester.tester setValue:[1, 2, 3, 4] forKey:@"subviews"];
-    [tester addObserver:self forKeyPath:@"tester.subviews" options:0 context:@"testChangeTopLevelObject"];
+    [tester addObserver:self forKeyPath:@"tester.subviews" options:CPKeyValueObservingOptionNew | CPKeyValueObservingOptionOld context:@"testChangeTopLevelObject"];
 
     var newTesterTester = [ToManyTester new];
     [newTesterTester setValue:[5, 6, 7, 8] forKey:@"subviews"];
@@ -554,7 +583,24 @@
             if (!_sawPriorObservation)
             {
                 [self assertTrue:prior message:@"Have not been sent the prior notification, but it should have been sent"];
-                [self assertTrue:oldValue == [CPNull null] message:@"Shoudl be no initial value"];
+                [self assertTrue:oldValue == [CPNull null] message:@"Should be no initial value"];
+                [self assertFalse:newValue message:@"Should be no object for the new value key on the prior notification"];
+                _sawPriorObservation = YES;
+            }
+            else
+            {
+                [self assertFalse:prior message:@"there should be no value for the notification is prior key, that notification was already sent"];
+                [self assertTrue:newValue == "set_bob" message:@"newValue should be: set_bob was: " + newValue];
+            }
+            break;
+
+        case "testPriorObservationOptionNoOld":
+            var prior = [changes objectForKey:CPKeyValueChangeNotificationIsPriorKey];
+
+            if (!_sawPriorObservation)
+            {
+                [self assertTrue:prior message:@"Have not been sent the prior notification, but it should have been sent"];
+                [self assertTrue:oldValue == nil message:@"Should be no old value"];
                 [self assertFalse:newValue message:@"Should be no object for the new value key on the prior notification"];
                 _sawPriorObservation = YES;
             }
@@ -568,8 +614,20 @@
         case "testInitialObservationOption":
             if (!_sawInitialObservation)
             {
-                [self assertTrue:newValue == "paul" message:@"Expected old value to be: paul was: " + oldValue];
-                [self assertFalse:oldValue message:@"Should be no value for new change key on initial observation"];
+                [self assertTrue:newValue == "paul" message:@"Expected new value to be: paul was: " + newValue];
+                [self assertTrue:oldValue == nil message:@"Should be no value for old change key on initial observation"];
+                _sawInitialObservation = YES;
+            }
+            else
+                [self assertFalse:YES message:@"Should never have received this notification"];
+
+            break;
+
+        case "testInitialObservationOptionNoNew":
+            if (!_sawInitialObservation)
+            {
+                [self assertTrue:newValue == nil message:@"New value should not be included"];
+                [self assertTrue:oldValue == nil message:@"Should be no value for old change key on initial observation"];
                 _sawInitialObservation = YES;
             }
             else

Tests/Foundation/CPKeyValueObservingTest.j

@@ -2,6 +2,7 @@
 @import <Foundation/CPKeyValueCoding.j>
 @import <Foundation/CPKeyValueObserving.j>
 
+var _getCheeseCounter;
 
 @implementation CPKeyValueObservingTest : OJTestCase
 {
@@ -9,6 +10,12 @@
     id              _lastObject;
     CPDictionary    _lastChange;
     id              _lastContext;
+
+    CPString        _secondLastKeyPath;
+    id              _secondLastObject;
+    CPDictionary    _secondLastChange;
+    id              _secondLastContext;
+
 }
 
 - (Class)objectWithMethods:(CPString)aMethodName, ...
@@ -26,9 +33,10 @@
     return [theClass new];
 }
 
-- (void)setup
+- (void)setUp
 {
-    _lastKeyPath = _lastObject = _lastChange = _lastContext = nil;
+    _lastKeyPath = _lastObject = _lastChange = _lastContext = _secondLastKeyPath = _secondLastObject = _secondLastChange = _secondLastContext = nil;
+    _getCheeseCounter = 0;
 }
 
 - (void)testInitialObserving
@@ -38,18 +46,210 @@
 
     [self assert:@"cheese" equals:_lastKeyPath];
     [self assert:tester equals:_lastObject];
-    [self assert:[CPDictionary dictionaryWithObject:@"CHEESE!" forKey:CPKeyValueChangeNewKey] equals:_lastChange];
+    [self assert:@{CPKeyValueChangeNewKey: @"CHEESE!", CPKeyValueChangeKindKey: CPKeyValueChangeSetting} equals:_lastChange];
     [self assert:nil equals:_lastContext];
 }
 
+- (void)testInitialObservingNoNew
+{
+    var tester = [ObservingTester testerWithCheese:@"CHEESE!"];
+    [tester addObserver:self forKeyPath:@"cheese" options:CPKeyValueObservingOptionInitial context:nil];
+
+    [self assert:@"cheese" equals:_lastKeyPath];
+    [self assert:tester equals:_lastObject];
+    [self assert:@{CPKeyValueChangeKindKey: CPKeyValueChangeSetting} equals:_lastChange];
+    [self assert:nil equals:_lastContext];
+}
+
+- (void)testSettingObservingPrior
+{
+    var tester = [ObservingTester testerWithCheese:@"CHEESE!"];
+    [tester addObserver:self forKeyPath:@"cheese" options:CPKeyValueObservingOptionPrior context:nil];
+
+    [tester setValue:@"NEW CHEESE!" forKey:@"cheese"];
+
+    [self assert:@"cheese" equals:_secondLastKeyPath];
+    [self assert:tester equals:_secondLastObject];
+    [self assert:@{CPKeyValueChangeKindKey: CPKeyValueChangeSetting, CPKeyValueChangeNotificationIsPriorKey: 1} equals:_secondLastChange];
+    [self assert:nil equals:_secondLastContext];
+
+    [self assert:@"cheese" equals:_lastKeyPath];
+    [self assert:tester equals:_lastObject];
+    [self assert:@{CPKeyValueChangeKindKey: CPKeyValueChangeSetting} equals:_lastChange];
+    [self assert:nil equals:_lastContext];
+    [self assert:0 equals:_getCheeseCounter message:@"Get method should never be called"];
+}
+
+- (void)testSettingObservingPriorPlusMoreObservers
+{
+    var tester = [ObservingTester testerWithCheese:@"CHEESE!"];
+    [tester addObserver:self forKeyPath:@"cheese" options:CPKeyValueObservingOptionPrior context:nil];
+
+    var observerWithOld = [[AnotherObserver alloc] init];
+    [tester addObserver:observerWithOld forKeyPath:@"cheese" options:CPKeyValueObservingOptionPrior | CPKeyValueObservingOptionOld context:nil];
+
+    var observerWithNew = [[AnotherObserver alloc] init];
+    [tester addObserver:observerWithNew forKeyPath:@"cheese" options:CPKeyValueObservingOptionPrior | CPKeyValueObservingOptionNew context:nil];
+
+    var observerWithNewAndOld = [[AnotherObserver alloc] init];
+    [tester addObserver:observerWithNewAndOld forKeyPath:@"cheese" options:CPKeyValueObservingOptionPrior | CPKeyValueObservingOptionOld | CPKeyValueObservingOptionNew context:nil];
+
+    [tester setValue:@"NEW CHEESE!" forKey:@"cheese"];
+
+    [self assert:@"cheese" equals:_secondLastKeyPath];
+    [self assert:tester equals:_secondLastObject];
+    [self assert:@{CPKeyValueChangeKindKey: CPKeyValueChangeSetting, CPKeyValueChangeNotificationIsPriorKey: 1} equals:_secondLastChange];
+    [self assert:nil equals:_secondLastContext];
+
+    [self assert:@"cheese" equals:_lastKeyPath];
+    [self assert:tester equals:_lastObject];
+    [self assert:@{CPKeyValueChangeKindKey: CPKeyValueChangeSetting} equals:_lastChange];
+    [self assert:nil equals:_lastContext];
+
+    [self assert:@"cheese" equals:observerWithOld._secondLastKeyPath];
+    [self assert:tester equals:observerWithOld._secondLastObject];
+    [self assert:@{CPKeyValueChangeOldKey: @"CHEESE!", CPKeyValueChangeKindKey: CPKeyValueChangeSetting, CPKeyValueChangeNotificationIsPriorKey: 1} equals:observerWithOld._secondLastChange];
+    [self assert:nil equals:observerWithOld._secondLastContext];
+
+    [self assert:@"cheese" equals:observerWithOld._lastKeyPath];
+    [self assert:tester equals:observerWithOld._lastObject];
+    [self assert:@{CPKeyValueChangeOldKey: @"CHEESE!", CPKeyValueChangeKindKey: CPKeyValueChangeSetting} equals:observerWithOld._lastChange];
+    [self assert:nil equals:observerWithOld._lastContext];
+
+    [self assert:@"cheese" equals:observerWithNew._secondLastKeyPath];
+    [self assert:tester equals:observerWithNew._secondLastObject];
+    [self assert:@{CPKeyValueChangeKindKey: CPKeyValueChangeSetting, CPKeyValueChangeNotificationIsPriorKey: 1} equals:observerWithNew._secondLastChange];
+    [self assert:nil equals:observerWithNew._secondLastContext];
+
+    [self assert:@"cheese" equals:observerWithNew._lastKeyPath];
+    [self assert:tester equals:observerWithNew._lastObject];
+    [self assert:@{CPKeyValueChangeNewKey: @"NEW CHEESE!", CPKeyValueChangeKindKey: CPKeyValueChangeSetting} equals:observerWithNew._lastChange];
+    [self assert:nil equals:observerWithNew._lastContext];
+
+    [self assert:@"cheese" equals:observerWithNewAndOld._secondLastKeyPath];
+    [self assert:tester equals:observerWithNewAndOld._secondLastObject];
+    [self assert:@{CPKeyValueChangeOldKey: @"CHEESE!", CPKeyValueChangeKindKey: CPKeyValueChangeSetting, CPKeyValueChangeNotificationIsPriorKey: 1} equals:observerWithNewAndOld._secondLastChange];
+    [self assert:nil equals:observerWithNewAndOld._secondLastContext];
+
+    [self assert:@"cheese" equals:observerWithNewAndOld._lastKeyPath];
+    [self assert:tester equals:observerWithNewAndOld._lastObject];
+    [self assert:@{CPKeyValueChangeNewKey: @"NEW CHEESE!", CPKeyValueChangeOldKey: @"CHEESE!", CPKeyValueChangeKindKey: CPKeyValueChangeSetting} equals:observerWithNewAndOld._lastChange];
+    [self assert:nil equals:observerWithNewAndOld._lastContext];
+
+    [self assert:2 equals:_getCheeseCounter message:@"Get method should only be called twice, not " + _getCheeseCounter + " times"];
+}
+
+- (void)testSettingObserving
+{
+    var tester = [ObservingTester testerWithCheese:@"CHEESE!"];
+    [tester addObserver:self forKeyPath:@"cheese" options:0 context:nil];
+
+    [tester setValue:@"NEW CHEESE!" forKey:@"cheese"];
+    [self assert:@"cheese" equals:_lastKeyPath];
+    [self assert:tester equals:_lastObject];
+    [self assert:@{CPKeyValueChangeKindKey: CPKeyValueChangeSetting} equals:_lastChange];
+    [self assert:nil equals:_lastContext];
+    [self assert:0 equals:_getCheeseCounter message:@"Get method should never be called"];
+}
+
+- (void)testSettingObservingNewPlusAnotherObserverWithNoNew
+{
+    var tester = [ObservingTester testerWithCheese:@"CHEESE!"];
+    [tester addObserver:self forKeyPath:@"cheese" options:CPKeyValueObservingOptionNew context:nil];
+
+    var anotherObserver = [[AnotherObserver alloc] init];
+    [tester addObserver:anotherObserver forKeyPath:@"cheese" options:0 context:nil];
+
+    [tester setValue:@"NEW CHEESE!" forKey:@"cheese"];
+
+    [self assert:@"cheese" equals:_lastKeyPath];
+    [self assert:tester equals:_lastObject];
+    [self assert:@{CPKeyValueChangeNewKey: @"NEW CHEESE!", CPKeyValueChangeKindKey: CPKeyValueChangeSetting} equals:_lastChange];
+    [self assert:nil equals:_lastContext];
+
+    [self assert:@"cheese" equals:anotherObserver._lastKeyPath];
+    [self assert:tester equals:anotherObserver._lastObject];
+    [self assert:@{CPKeyValueChangeKindKey: CPKeyValueChangeSetting} equals:anotherObserver._lastChange];
+    [self assert:nil equals:anotherObserver._lastContext];
+
+    [self assert:1 equals:_getCheeseCounter message:@"Get method should only be called once, not " + _getCheeseCounter + " times"];
+}
+
+- (void)testSettingObservingOldPlusAnotherObserverWithNoOld
+{
+    var tester = [ObservingTester testerWithCheese:@"CHEESE!"];
+    [tester addObserver:self forKeyPath:@"cheese" options:CPKeyValueObservingOptionOld context:nil];
+
+    var anotherObserver = [[AnotherObserver alloc] init];
+    [tester addObserver:anotherObserver forKeyPath:@"cheese" options:0 context:nil];
+
+    [tester setValue:@"NEW CHEESE!" forKey:@"cheese"];
+
+    [self assert:@"cheese" equals:_lastKeyPath];
+    [self assert:tester equals:_lastObject];
+    [self assert:@{CPKeyValueChangeOldKey: @"CHEESE!", CPKeyValueChangeKindKey: CPKeyValueChangeSetting} equals:_lastChange];
+    [self assert:nil equals:_lastContext];
+
+    [self assert:@"cheese" equals:anotherObserver._lastKeyPath];
+    [self assert:tester equals:anotherObserver._lastObject];
+    [self assert:@{CPKeyValueChangeKindKey: CPKeyValueChangeSetting} equals:anotherObserver._lastChange];
+    [self assert:nil equals:anotherObserver._lastContext];
+
+    [self assert:1 equals:_getCheeseCounter message:@"Get method should only be called once, not " + _getCheeseCounter + " times"];
+}
+
+- (void)testSettingObservingNewAndOldPlusMoreObserversWithOnlyNewOrOld
+{
+    var tester = [ObservingTester testerWithCheese:@"CHEESE!"];
+    [tester addObserver:self forKeyPath:@"cheese" options:CPKeyValueObservingOptionNew | CPKeyValueObservingOptionOld context:nil];
+
+    var anotherObserver = [[AnotherObserver alloc] init];
+    [tester addObserver:anotherObserver forKeyPath:@"cheese" options:CPKeyValueObservingOptionOld context:nil];
+
+    var yetAnotherObserver = [[AnotherObserver alloc] init];
+    [tester addObserver:yetAnotherObserver forKeyPath:@"cheese" options:CPKeyValueObservingOptionNew context:nil];
+
+    var noNewOrOldObserver = [[AnotherObserver alloc] init];
+    [tester addObserver:noNewOrOldObserver forKeyPath:@"cheese" options:0 context:nil];
+
+    [tester setValue:@"NEW CHEESE!" forKey:@"cheese"];
+
+    [self assert:@"cheese" equals:_lastKeyPath];
+    [self assert:tester equals:_lastObject];
+    [self assert:@{CPKeyValueChangeNewKey: @"NEW CHEESE!", CPKeyValueChangeOldKey: @"CHEESE!", CPKeyValueChangeKindKey: CPKeyValueChangeSetting} equals:_lastChange];
+    [self assert:nil equals:_lastContext];
+
+    [self assert:@"cheese" equals:anotherObserver._lastKeyPath];
+    [self assert:tester equals:anotherObserver._lastObject];
+    [self assert:@{CPKeyValueChangeOldKey: @"CHEESE!", CPKeyValueChangeKindKey: CPKeyValueChangeSetting} equals:anotherObserver._lastChange];
+    [self assert:nil equals:anotherObserver._lastContext];
+
+    [self assert:@"cheese" equals:yetAnotherObserver._lastKeyPath];
+    [self assert:tester equals:yetAnotherObserver._lastObject];
+    [self assert:@{CPKeyValueChangeNewKey: @"NEW CHEESE!", CPKeyValueChangeKindKey: CPKeyValueChangeSetting} equals:yetAnotherObserver._lastChange];
+    [self assert:nil equals:yetAnotherObserver._lastContext];
+
+    [self assert:@"cheese" equals:noNewOrOldObserver._lastKeyPath];
+    [self assert:tester equals:noNewOrOldObserver._lastObject];
+    [self assert:@{CPKeyValueChangeKindKey: CPKeyValueChangeSetting} equals:noNewOrOldObserver._lastChange];
+    [self assert:nil equals:noNewOrOldObserver._lastContext];
+
+    [self assert:2 equals:_getCheeseCounter message:@"Get method should only be called twice even with many observers, not " + _getCheeseCounter + " times"];
+}
+
 - (void)observeValueForKeyPath:(CPString)aKeyPath
                       ofObject:(id)anObject
                         change:(CPDictionary)aChange
                        context:(id)aContext
 {
+    _secondLastKeyPath = _lastKeyPath;
+    _secondLastObject  = _lastObject;
+    _secondLastChange  = _lastChange;
+    _secondLastContext = _lastContext;
+
     _lastKeyPath = aKeyPath;
     _lastObject  = anObject;
-    _lastChange  = aChange;
+    _lastChange  = [aChange copy];
     _lastContext = aContext;
 }
 
@@ -244,6 +444,7 @@
 
 - (id)cheese
 {
+    _getCheeseCounter++;
     return cheese;
 }
 
@@ -280,3 +481,34 @@
 }
 
 @end
+
+@implementation AnotherObserver : CPObject
+{
+    CPString        _lastKeyPath;
+    id              _lastObject;
+    CPDictionary    _lastChange;
+    id              _lastContext;
+
+    CPString        _secondLastKeyPath;
+    id              _secondLastObject;
+    CPDictionary    _secondLastChange;
+    id              _secondLastContext;
+}
+
+- (void)observeValueForKeyPath:(CPString)aKeyPath
+                      ofObject:(id)anObject
+                        change:(CPDictionary)aChange
+                       context:(id)aContext
+{
+    _secondLastKeyPath = _lastKeyPath;
+    _secondLastObject  = _lastObject;
+    _secondLastChange  = _lastChange;
+    _secondLastContext = _lastContext;
+
+    _lastKeyPath = aKeyPath;
+    _lastObject  = anObject;
+    _lastChange  = [aChange copy];
+    _lastContext = aContext;
+}
+
+@end