曾经对 TMemoryStream.Memory 错误的理解

TMemoryStream 的 Position 变化后, 我曾经认为它的 Memory 属性也会变化; 只怪不看源码, 只想当然!

procedure TForm1.FormCreate(Sender: TObject);
var
  Stream1,Stream2: TMemoryStream;
  pw: TPtrWrapper;
begin
  Stream1 := TStringStream.Create('1234567890');
  Stream2 := TStringStream.Create('ABCDEFGHIJ');

  //想把 Stream1 变成 123DEFG890
  pw := TPtrWrapper.Create(Stream2.Memory);
  pw := TPtrWrapper.Create(pw.ToInteger + 3);

  Stream1.Position := 3;
  Stream1.Write(pw.ToPointer^, 4);

  ShowMessage(TStringStream(Stream1).DataString); //123DEFG890

  Stream1.Free;
  Stream2.Free;
end;