Objekt incl. untergeordnete objecte

[DeddyH]

Mal eben heruntergetippt, keine Garantie auf Fehlerfreiheit

Delphi-Quellcode:

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, ExtCtrls;

type
  //simuliertes Unterobjekt
  TDummyData = class
  private
    FString: string;
    FInteger: integer;
  public
    property StringVal: string read FString write FString;
    property IntVal: integer read FInteger write FInteger;
  end;

  //Klasse mit Kopierfunktion
  TBaseDummy = class(TPersistent)
  private
    FDummy: TDummyData;
  public
    constructor Create;
    destructor Destroy; override;
    //Überschreiben von AssignTo
    procedure AssignTo(Dest: TPersistent); override;
    property Dummy: TDummyData read FDummy;
  end;

  TForm1 = class(TForm)
    Button1: TButton;
    Button2: TButton;
    Image1: TImage;
    procedure FormCreate(Sender: TObject);
    procedure FormDestroy(Sender: TObject);
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
  private
    { Private-Deklarationen }
    FTest1, FTest2: TBaseDummy;
  public
    { Public-Deklarationen }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

{ TBaseDummy }

procedure TBaseDummy.AssignTo(Dest: TPersistent);
begin
  //wenn Dest ein TBaseDummy ist, Werte kopieren
  if Assigned(Dest) and (Dest is TBaseDummy) then
    begin
      TBaseDummy(Dest).Dummy.StringVal := FDummy.StringVal;
      TBaseDummy(Dest).Dummy.IntVal := FDummy.IntVal;
    end
  else
    inherited AssignTo(Dest);
end;

constructor TBaseDummy.Create;
begin
  inherited;
  FDummy := TDummyData.Create;
end;

destructor TBaseDummy.Destroy;
begin
  FDummy.Free;
  inherited;
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
  //aktuelle Werte des 2. Objektes anzeigen
  ShowMessage(Format('%s: %d',[FTest2.Dummy.StringVal,FTest2.Dummy.IntVal]));
end;

procedure TForm1.Button2Click(Sender: TObject);
begin
  //Werte kopieren
  FTest2.Assign(FTest1);
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
  FTest1 := TBaseDummy.Create;
  FTest1.Dummy.StringVal := 'Erster String';
  FTest1.Dummy.IntVal := 1;
  FTest2 := TBaseDummy.Create;
  FTest2.Dummy.StringVal := 'Zweiter String';
  FTest2.Dummy.IntVal := 2;
end;

procedure TForm1.FormDestroy(Sender: TObject);
begin
  FTest1.Free;
  FTest2.Free;
end;

end.