Delphi泛型TObjectList继承

我想创建一个TObjectList< T>后代来处理我的应用程序中的对象列表之间的常见功能.然后我想进一步从新类继续下载,以便在需要时引入其他功能.我似乎无法使用超过1级的继承.我可能需要更多地了解泛型,但是我搜索高低都是正确的方法来做到这一点而没有成功.到目前为止,这是我的代码：

unit edGenerics;

interface

uses
  Generics.Collections;

type

  TObjectBase = class
  public
    procedure SomeBaseFunction;
  end;

  TObjectBaseList<T: TObjectBase> = class(TObjectList<T>)
  public
    procedure SomeOtherBaseFunction;
  end;

  TIndexedObject = class(TObjectBase)
  protected
    FIndex: Integer;
  public
    property Index: Integer read FIndex write FIndex;
  end;

  TIndexedObjectList<T: TIndexedObject> = class(TObjectBaseList<T>)
  private
    function GetNextAutoIndex: Integer;
  public
    function Add(AObject: T): Integer;
    function ItemByIndex(AIndex: Integer): T;
    procedure Insert(AIndex: Integer; AObject: T);
  end;

  TCatalogueItem = class(TIndexedObject)
  private
    FID: integer;
  public
    property ID: integer read FId write FId;
  end;

  TCatalogueItemList = class(TIndexedObjectList<TCatalogueItem>)
  public
    function GetRowById(AId: Integer): Integer;
  end;

implementation

uses
  Math;

{ TObjectBase }

procedure TObjectBase.SomeBaseFunction;
begin
end;

{ TObjectBaseList<T> }

procedure TObjectBaseList<T>.SomeOtherBaseFunction;
begin
end;

{ TIndexedObjectList }

function TIndexedObjectList<T>.Add(AObject: T): Integer;
begin
  AObject.Index := GetNextAutoIndex;
  Result := inherited Add(AObject);
end;

procedure TIndexedObjectList<T>.Insert(AIndex: Integer; AObject: T);
begin
  AObject.Index := GetNextAutoIndex;
  inherited Insert(AIndex,AObject);
end;

function TIndexedObjectList<T>.ItemByIndex(AIndex: Integer): T;
var
  I: Integer;
begin
  Result := Default(T);
  while (Count > 0) and (I < Count) and (Result = Default(T)) do
    if Items[I].Index = AIndex then
      Result := Items[I]
    else
      Inc(I);
end;

function TIndexedObjectList<T>.GetNextAutoIndex: Integer;
var
  I: Integer;
begin
  Result := 0;
  for I := 0 to Count - 1 do
    Result := Max(Result,Items[I].Index);
  Inc(Result);
end;

{ TCatalogueItemList }

function TCatalogueItemList.GetRowById(AId: Integer): Integer;
var
  I: Integer;
begin
  Result := -1;
  for I := 0 to Pred(Self.Count) do
    if Self.Items[I].Id = AId then
    begin
      Result := I;
      Break;
    end;
end;

end.
/////// ERROR HAPPENS HERE ////// ???? why is beyond me

看来,以下声明：

>>> TCatalogueItemList = class(TIndexedObjectList<TCatalogueItem>) <<<<

导致以下编译器错误：

[DCC Error] edGenerics.pas(106): E2010 Incompatible types:
‘TCatalogueItem’ and ‘TIndexedObject’

然而,编译器在编译单元的END处显示错误(第106行),而不是在声明本身上显示错误,这对我没有任何意义……

基本上我的想法是我有一个从TObjectList开始的通用列表,我可以根据需要扩展新功能.对此有任何帮助将是伟大的！

我应该使用Delphi 2010添加.

谢谢.

TIndexedObjectList<T>.ItemByIndex(AIndex: Integer): T;

Result := TIndexedObject(nil);

function TCatalogueItemList.ItemByIndex(AIndex: Integer): TCatalogueItem;
begin
  Result := TIndexedObject(nil);  //did you see the problem now?

Result := Default(T);

Result := T(nil);
//or 
Result := T(SomeOtherValue);

Result := nil;