Rewrote the list variant of the OnItemRefreshed() operator, in accordance with #1014. (#1068)

Author: JakenVeina

src/DynamicData.Tests/API/ApiApprovalTests.DynamicDataTests.DotNet9_0.verified.txt

@@ -2389,8 +2389,8 @@ namespace DynamicData
             where T :  notnull { }
         public static System.IObservable<DynamicData.IChangeSet<T>> OnItemAdded<T>(this System.IObservable<DynamicData.IChangeSet<T>> source, System.Action<T> addAction)
             where T :  notnull { }
-        public static System.IObservable<DynamicData.IChangeSet<TObject>> OnItemRefreshed<TObject>(this System.IObservable<DynamicData.IChangeSet<TObject>> source, System.Action<TObject> refreshAction)
-            where TObject :  notnull { }
+        public static System.IObservable<DynamicData.IChangeSet<T>> OnItemRefreshed<T>(this System.IObservable<DynamicData.IChangeSet<T>> source, System.Action<T> refreshAction)
+            where T :  notnull { }
         public static System.IObservable<DynamicData.IChangeSet<T>> OnItemRemoved<T>(this System.IObservable<DynamicData.IChangeSet<T>> source, System.Action<T> removeAction, bool invokeOnUnsubscribe = true)
             where T :  notnull { }
         public static System.IObservable<DynamicData.IChangeSet<T>> Or<T>(this DynamicData.IObservableList<DynamicData.IObservableList<T>> sources)
@@ -3100,4 +3100,4 @@ namespace DynamicData.Tests
         public void Dispose() { }
         protected virtual void Dispose(bool isDisposing) { }
     }
-}
+}

src/DynamicData/List/Internal/OnItemRefreshed.cs

@@ -0,0 +1,28 @@
+// Copyright (c) 2011-2025 Roland Pheasant. All rights reserved.
+// Roland Pheasant licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for full license information.
+
+using System.Reactive.Linq;
+
+namespace DynamicData.List.Internal;
+
+internal static class OnItemRefreshed<T>
+    where T : notnull
+{
+    public static IObservable<IChangeSet<T>> Create(
+        IObservable<IChangeSet<T>> source,
+        Action<T> refreshAction)
+    {
+        source.ThrowArgumentNullExceptionIfNull(nameof(source));
+        refreshAction.ThrowArgumentNullExceptionIfNull(nameof(refreshAction));
+
+        return source.Do(changeSet =>
+        {
+            foreach (var change in changeSet)
+            {
+                if (change.Reason is ListChangeReason.Refresh)
+                    refreshAction.Invoke(change.Item.Current);
+            }
+        });
+    }
+}

src/DynamicData/List/ObservableListEx.cs

@@ -1259,29 +1259,21 @@ public static IObservable<IChangeSet<T>> OnItemAdded<T>(
             addAction: addAction);
 
     /// <summary>
-    /// Callback for each item as and when it is being refreshed in the stream.
+    /// Invokes a given action for every item refreshed within the source list stream.
     /// </summary>
-    /// <typeparam name="TObject">The type of the object.</typeparam>
-    /// <param name="source">The source.</param>
-    /// <param name="refreshAction">The refresh action.</param>
-    /// <returns>An observable which emits a change set with items being added.</returns>
-    public static IObservable<IChangeSet<TObject>> OnItemRefreshed<TObject>(this IObservable<IChangeSet<TObject>> source, Action<TObject> refreshAction)
-        where TObject : notnull
-    {
-        var refreshAction2 = refreshAction;
-        if (source == null)
-        {
-            throw new ArgumentNullException(nameof(source));
-        }
-
-        if (refreshAction2 == null)
-        {
-            throw new ArgumentNullException(nameof(refreshAction));
-        }
-
-        return source.Do((IChangeSet<TObject> changes) =>
-            changes.Where((Change<TObject> c) => c.Reason == ListChangeReason.Refresh).ForEach((Change<TObject> c) => refreshAction2(c.Item.Current)));
-    }
+    /// <typeparam name="T">The type of items in the list.</typeparam>
+    /// <param name="source">The list stream whose items are to be passed to <paramref name="refreshAction"/>.</param>
+    /// <param name="refreshAction">The action to invoke upon each refreshed item.</param>
+    /// <returns>A list stream, containing all items in <paramref name="source"/>, with changes published after <paramref name="refreshAction"/> has been invoked.</returns>
+    /// <exception cref="ArgumentNullException">Throws for <paramref name="source"/> and <paramref name="refreshAction"/>.</exception>
+    /// <remarks>Note that "refreshed" items refers to items from <see cref="ListChangeReason.Refresh"/> changes.</remarks>
+    public static IObservable<IChangeSet<T>> OnItemRefreshed<T>(
+                this IObservable<IChangeSet<T>> source,
+                Action<T> refreshAction)
+            where T : notnull
+        => List.Internal.OnItemRefreshed<T>.Create(
+            source: source,
+            refreshAction: refreshAction);
 
     /// <summary>
     /// Callback for each item as and when it is being removed from the stream.