Wie testet man ob Enum in Teilgruppe davon?

[xZise]

Moin,
und wenn es nicht nur um Elemente geht:

Delphi-Quellcode:

type
  TFixelType = (ftWall, ftBall, ftFinish,
                ftRedBrush, ftGreenBrush, ftYellowBrush,  ftBlueBrush,
                ftAcid,
                ftRedSwitch, ftGreenSwitch, ftYellowSwitch, ftBlueSwitch,
                ftRedDoor, ftGreenDoor, ftYellowDoor, ftBlueDoor,
                ftBumper, ftPad,
                ftRedAccelerator, ftGreenAccelerator, ftYellowAccelerator, ftBlueAccelerator,
                ftRedBeamstart, ftGreenBeamstart, ftYellowBeamstart, ftBlueBeamstart,
                ftRedBeamtarget, ftGreenBeamtarget, ftYellowBeamtarget, ftBlueBeamtarget,
                ftBlocker,
                ftText);

const
  DOOR_TYPES = [ftRedDoor, ftGreenDoor, ftYellowDoor, ftBlueDoor];
  BRUSHES_TYPES = [ftRedBrush, ftGreenBrush, ftYellowBrush, ftBlueBrush];

Klar, dort könnte ich auch eine verschachtelte if-Abfrage machen, aber case ist da meiner Meinung nach schöner:

Delphi-Quellcode:

case TFixelType(AMainRec.Bytes[2] - 1) of
  ftWall : ASprteBuf := TVirtualWall.Create;
  ftRedBrush, ftGreenBrush, ftYellowBrush, ftBlueBrush : ASprteBuf := TVirtualBrush.Create;
//  DOOR_TYPES : ASprteBuf := TVirtualDoor.Create;
  ftRedDoor, ftGreenDoor, ftYellowDoor, ftBlueDoor : ASprteBuf := TVirtualDoor.Create;
  else ASprteBuf := TVirtualFixel.Create;
end;

MfG
Fabian