Answer to Exercise 31

| ANSWER TO EXERCISE 31
| Martha and the sealed room are defined as follows:
    Object sealed_room "Sealed Room"
      with description
              "I'm in a sealed room, like a squash court without a door,
               maybe six or seven yards across",
      has  light;
    Object -> ball "red ball" with name "red" "ball";
    Object -> martha "Martha"
      with name "martha",
           orders
           [ r; r=parent(self);
               Give:
                   if (noun notin r) "~That's beyond my telekinesis.~";
                   if (noun==self) "~Teleportation's too hard for me.~";
                   move noun to player;
                   "~Here goes...~ and Martha's telekinetic talents
                       magically bring ", (the) noun, " to your hands.";
               Look:
                   print "~", (string) r.description;
                   if (children(r)==1) ".  There's nothing here but me.~";
                   print ".  I can see ";
                   WriteListFrom(child(r),CONCEAL_BIT+ENGLISH_BIT);
                  ".~";
               default: "~Afraid I can't help you there.~";
           ],
           life
           [;  Ask: "~You're on your own this time.~";
               Tell: "Martha clucks sympathetically.";
               Answer: "~I'll be darned,~ Martha replies.";
           ],
       has animate female concealed proper;
but the really interesting part is the `InScope` routine to fix things up:
    [ InScope actor;
       if (actor==martha) PlaceInScope(player);
       if (actor==player && scope_reason==TALKING_REASON)
           PlaceInScope(martha);
       rfalse;
    ];
Note that since we want two-way communication, the player has to be in scope to Martha too: otherwise Martha won't be able to follow the command "martha, give me the fish'', because "me'' will refer to something beyond her scope.

Back to the exercise in section 16

Mechanically translated to HTML from third edition as revised 16 May 1997. Copyright © Graham Nelson 1993, 1994, 1995, 1996, 1997: all rights reserved.