Answer to Exercise 87

ANSWER TO EXERCISE 87

Firstly, create an attribute is_key and give it to all the keys in the game. Then:

Global assumed_key;
[ DefaultLockSub;
  print "(with ", (the) assumed_key, ")^"; <<Lock noun assumed_key>>;
];
[ DefaultLockTest i count;
  if (noun hasnt lockable) rfalse;
  objectloop (i in player)
      if (i has is_key) { count++; assumed_key = i; }
  if (count==1) rtrue; rfalse;
];
Extend "lock" first * noun = DefaultLockTest -> DefaultLock;

(and similar code for "unlock''). Note that "lock strongbox'' is matched by this new grammar line only if the player only has one key: the DefaultLock strongbox action is generated: which is converted to, say, Lock strongbox brass_key.

Back to the exercise in section 29