property特性

 TVirtualProperty = class
  private
    FSomeData:string;
  protected
    function  GetSomeData:string;virtual;
    procedure SetSomeData(const value:string);virtual;
  public
    property SomeData:string read GetSomeData write SetSomeData;
  end;

  TSubClass = class(TVirtualProperty)
  protected
    function GetSomeData:string;override;
    procedure SetSomeData(const value:string);override;
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.FormCreate(Sender: TObject);
var
  vp:TVirtualProperty;
begin
  vp:=tsubclass.Create;
  try
      vp.SomeData:='Follow me';
      showmessage(vp.SomeData);
  finally
      vp.Free;
  end;
end;

{ TVirtualProperty }

function TVirtualProperty.GetSomeData: string;
begin
   result:=FSomeData;
end;

procedure TVirtualProperty.SetSomeData(const value: string);
begin
   FSomeData:=value;
end;

{ TSubClass }

function TSubClass.GetSomeData: string;
begin
   result:= inherited GetSomeData;
end;

procedure TSubClass.SetSomeData(const value: string);
begin
 // inherited;
  if (someData= value) then exit;
  inherited SetSomeData(value);
end;

end.