Make it possible to gather values using scoped ItemConfiguration

Toolkit.Foundation/ICollectionSynchronization.cs

@@ -0,0 +1,3 @@
+namespace Toolkit.Foundation;
+
+public interface ICollectionSynchronization<TItem>;

Toolkit.Foundation/ICollectionSynchronizationExtensions.cs

@@ -0,0 +1,7 @@
+namespace Toolkit.Foundation;
+
+public static class ICollectionSynchronizationExtensions
+{
+    public static int IndexOf<TItem>(this ICollectionSynchronization<TItem> synchronization,
+        TItem item) => synchronization is IList<TItem> collection ? collection.IndexOf(item) : -1;
+}

Toolkit.Foundation/IIndexed.cs

@@ -1,6 +1,6 @@
 namespace Toolkit.Foundation;
 
-public interface IIndexable
+public interface IIndexed
 {
     public int Index { get; }
-}
+}

Toolkit.Foundation/IKeyed.cs

@@ -0,0 +1,6 @@
+namespace Toolkit.Foundation;
+
+public interface IKeyed<T>
+{
+    public T Id { get; }
+}

Toolkit.Foundation/ISynchronizationCollection.cs

@@ -1,6 +0,0 @@
-namespace Toolkit.Foundation;
-
-public interface ISynchronizationCollection<TItem>
-{
-    int IndexOf(TItem item);
-}

Toolkit.Foundation/Observable.cs

@@ -1,4 +1,5 @@
 using CommunityToolkit.Mvvm.ComponentModel;
+using System.ComponentModel;
 
 namespace Toolkit.Foundation;
 
@@ -140,4 +141,11 @@ public partial class Observable<TKey, TValue> : Observable
         Key = key;
         Value = value;
     }
+
+    partial void OnValueChanged(TValue? value) => OnValueChanged();
+
+    protected virtual void OnValueChanged()
+    {
+
+    }
 }

Toolkit.Foundation/ObservableCollection.cs

@@ -18,7 +18,7 @@ public partial class ObservableCollection<TItem> :
     IList,
     IReadOnlyList<TItem>,
     INotifyCollectionChanged,
-    ISynchronizationCollection<TItem>,
+    ICollectionSynchronization<TItem>,
     IServiceProviderRequired,
     IServiceFactoryRequired,
     IMediatorRequired,