Reference TObjectList<TItem>

  TObjectList<TItem: TObject> = class(TIndexedList<TItem>)
  protected
    { Prevents items from being added twice }
    procedure AddItem(constref Item: ItemType); override;
    { Frees the items if the list owns the objects }
    procedure DeleteItem(var Item: ItemType); override;
    { Returns true if the list owns the objects }
    function RequiresDelete: Boolean; override;
  public
    { Create the list optionally owning objects added to it }
    constructor Create(OwnsObjects: Boolean);
    { Returns the index of the object or -1 if it cannot be found }
    function IndexOf(const Item: ItemType): Integer; override;
    { Allow, ignore, or error on adding a duplicate object }
    property Duplicates;
  end;