小编Lou*_*man的帖子

我正在使用Delphi XE来实现一个枚举器,它允许按类型过滤列表中的元素.我已经快速组装了一个测试单元如下:

unit uTestList;

interface

uses Generics.Collections;

type
  TListItemBase = class(TObject)
  end; { TListItemBase }

  TListItemChild1 = class(TListItemBase)
  end;

  TListItemChild2 = class(TListItemBase)
  end;

  TTestList<T : TListItemBase> = class;

  TOfTypeEnumerator<T, TFilter> = class(TInterfacedObject, IEnumerator<TFilter>)
  private
    FTestList : TList<T>;
    FIndex : Integer;
  protected
    constructor Create(Owner : TList<T>); overload;

    function GetCurrent : TFilter;
    function MoveNext : Boolean;
    procedure Reset;

    function IEnumerator<TFilter>.GetCurrent = GetCurrent;
    function IEnumerator<TFilter>.MoveNext = MoveNext;
    procedure IEnumerator<TFilter>.Reset = Reset;
  end;

  TOfTypeEnumeratorFactory<T, TFilter> = class(TInterfacedObject, IEnumerable)
  private
    FTestList : TList<T>;
  public
    constructor …