Question

我需要实现控件的TList后代+额外的对象类似的东西：

List.Add(AControl, AObject)

因此，列表将同时包含AControl, AObject

使用Delphi 7执行此操作的最佳方法是什么？

Answer 1

您可以存储记录列表，然后您可以将任何您想要的内容放入记录中，例如：

type
  PMyRecord = ^MyRecord;
  MyRecord = record
    Control: TControl;
    Object: TObject;
  end;

var
  Rec: PMyRecord;
begin
  New(Rec);
  try
    Rec.Control := AControl;
    Rec.Object := AObject;
    List.Add(Rec);
  except
    Dispose(Rec);
    Raise;
  end;
end;

var
  Rec: PMyRecord;
begin
  Rec := PMyRecord(List[SomeIndex]);
  // use Rec.Control and Rec.Object as needed...
end;

从列表中删除项目时，不要忘记Dispose()项目：

var
  Rec: PMyRecord;
begin
  Rec := PMyRecord(List[SomeIndex]);
  List.Delete(SomeIndex);
  Dispose(Rec);
end;

此外，当您使用完列表时，或者至少在您使用Clear()时：

var
  I: Integer;
  Rec: PMyRecord;
begin
  for I := o to List.Count-1 do
    Dispose(PMyRecord(List[I]));
  //...
end;

如果从TList派生新类，则可以覆盖其虚拟Notify()方法来处置项目：

type
  TMyList = class(TList)
  protected
    function Get(Index: Integer): PMyRecord;
    procedure Notify(Ptr: Pointer; Action: TListNotification); override;
  public
    function Add(AControl: TControl; AObject: TObject): Integer;
    procedure Insert(Index: Integer; AControl: TControl; AObject: TObject);
    property Items[Index: Integer]: PMyRecord read Get; default;
  end;

function TMyList.Add(AControl: TControl; AObject: TObject): Integer;
var
  Rec: PMyRecord;
begin
  New(Rec);
  try
    Rec.Control := AControl;
    Rec.Object := AObject;
    Result := inherited Add(Rec);
  except
    Dispose(Rec);
    Raise;
  end;
end;

procedure TMyList.Insert(Index: Integer; AControl: TControl; AObject: TObject);
var
  Rec: PMyRecord;
begin
  New(Rec);
  try
    Rec.Control := AControl;
    Rec.Object := AObject;
    inherited Insert(Index, Rec);
  except
    Dispose(Rec);
    Raise;
  end;
end;

function TMyList.Get(Index: Integer): PMyRecord;
begin
  Result := PMyRecord(inherited Get(Index));
end;

procedure TMyList.Notify(Ptr: Pointer; Action: TListNotification);
begin
  inherited;
  if Action = lnDeleted then
    Dispose(PMyRecord(Ptr));
end;

Answer 2

试试这个

type
  TForm1 = class(TForm)
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

  TMyContainer = class
  public
     ctnGen: TControl;
     objGen: TObject;
     constructor Create(const ctnGen: TControl; const objGen: TObject);
  end;

var
  Form1: TForm1;

implementation

uses
  Contnrs;

{$R *.DFM}

{ TMyContainer }

constructor TMyContainer.Create(const ctnGen: TControl;
  const objGen: TObject);
begin
   inherited Create();
   Self.ctnGen := ctnGen;
   Self.objGen := objGen;
end;

procedure TForm1.Button1Click(Sender: TObject);
var
   lstGen: TObjectList;
begin
   lstGen := TObjectList.Create(True);
   try
      lstGen.Add(TMyContainer.Create(Self, Self));
      ShowMessage(TMyContainer(lstGen.Items[0]).objGen.ClassName);
   finally
      lstGen.Free;
   end;                                          
end;

TObjectList将释放TMyContainer类

TList后代与另一个对象？

2 个答案: