A shipboard room. This is a simple mix-in class: it can be used along with any type of Room to indicate that this room is aboard a ship. When a room is aboard a ship, the shipboard travel directions (port, starboard, fore, aft) are allowed; these directions normally make no sense.

This is a mix-in class rather than a Room subclass to allow it to be used in conjunction with any other Room subclass. To make a room shipboard, simply declare your room like this:

mainDeck: Shipboard, Room // etc

class Shipboard :   object