Fix bug that causes crash in ReactiveCollection[n] = Foo

reactiveui · Oct 31, 2010 · 72fadbe · 72fadbe
1 parent 6b334ef
commit 72fadbe
Showing 1 changed file with 5 additions and 1 deletion.
diff --git a/ReactiveXaml/ReactiveCollection.cs b/ReactiveXaml/ReactiveCollection.cs
@@ -210,9 +210,13 @@ public ReactiveCollection<TNew> CreateDerivedCollection<TNew>(Func<T, TNew> Sele
                 case NotifyCollectionChangedAction.Add:
                 case NotifyCollectionChangedAction.Remove:
                 case NotifyCollectionChangedAction.Replace:
+                    // NB: SL4 fills in OldStartingIndex with -1 on Replace :-/
+                    int old_index = (x.EventArgs.Action == NotifyCollectionChangedAction.Replace ?
+                        x.EventArgs.NewStartingIndex : x.EventArgs.OldStartingIndex);
+
                     if (x.EventArgs.OldItems != null) {
                         foreach(object _ in x.EventArgs.OldItems) {
-                            ret.RemoveAt(x.EventArgs.OldStartingIndex);
+                            ret.RemoveAt(old_index);
                         }
                     }
                     if (x.EventArgs.NewItems != null) {