Reference TNotifyCollection<T>

  TNotifyCollection<T: TCollectionItem> = class(TCollection)
  protected
    function GetOwner: TPersistent; override;
    { Invoke OnItemNotify subscribers }
    procedure Notify(Item: TCollectionItem; Action: TCollectionNotification); override;
    { Invoke OnItemUpdate subscribers }
    procedure Update(Item: TCollectionItem); override;
  public
    { Create a collection owned by a persistent object }
    constructor Create(AOwner: TPersistent); virtual;
    destructor Destroy; override;
    { Copy the items of another collection }
    procedure Assign(Source: TPersistent); override;
    { Add a new item }
    function Add: T;
    { The object which owns the collection }
    property Owner: TPersistent read FOwner;
    { Items indexed by an integer }
    property Items[const Index: Integer]: T read GetItem write SetItem; default;
    { Subscribe to notifications when items are added or removed }
    property OnItemNotify: IItemNotifyDelegate read GetOnItemNotify;
    { Subscribe to notifications when items change }
    property OnItemUpdate: IItemUpdateDelegate read GetOnItemUpdate;
  end;