Clearly, we should come back and expand the desc method once we've implemented more of the locations the ship can go to. The points to note here are (1) that desc() can be a method (in which case we need to name it explicitly, not via the template) and (2) to remember to use the break statement in each branch of the switch statement where we don't want fall-through.
Note that the OutOfReach class, which we shall encounter later, can sometimes offer a more flexible way of implementing distant objects; especially when they may become reachable under certain conditions.