'宣言
Public Class ReadOnlyKeyedObservableCollection
(Of TItem As {Class, INotifyPropertyChanged},
TKey)
Inherits System.Collections.ObjectModel.ReadOnlyObservableCollection(Of TItem)
Implements IKeyedList(Of TItem,TKey)
public class ReadOnlyKeyedObservableCollection<TItem,TKey> : System.Collections.ObjectModel.ReadOnlyObservableCollection<TItem>, IKeyedList<TItem,TKey> where TItem: class, INotifyPropertyChanged