delphi property read writer 如何使用

type
  TMyClass = class(TObject)
  private
    FMyName: string;
    FMyAge: Integer;
    procedure SetAge(age: Integer);
    function GetAge(): Integer;
  published
    property MyName: string read FMyName write FMyName;
    property MyAge: Integer read GetAge write SetAge;
  end;

procedure TMyClass.SetAge(age: Integer);
begin
  if (age < 0) or (age > 200) then
    ShowMessage('当前设置的年龄数值: ' + IntToStr(age) + '不是有效的年龄数值')
  else FMyAge := age;
end;

function TmyClass.GetAge: Integer;
begin
  Result := FMyAge;
end;

// 测试
procedure TForm1.Button1Click(Sender: TObject);
var
  ta: TMyClass;
begin
  ta := TMyClass.Create;
  ShowMessage('myname:' + ta.MyName + ', myage:' + IntToStr(ta.MyAge));
  ta.MyName := 'Tom';
  ta.MyAge := -10;
  ShowMessage('myname:' + ta.MyName + ', myage:' + IntToStr(ta.MyAge));
  ta.MyAge := 22;
  ShowMessage('myname:' + ta.MyName + ', myage:' + IntToStr(ta.MyAge));
  ta.free;
end;