7 | |CENTER| *U was a usurer, a miserable elf;*
8 | |CENTER| *V was a vintner, who drank all himself.*
12 .. image:: /images/picV.png
15 |V|\iewed from the inside, Benny's café is warm and welcoming, and packed
16 with lunchtime customers. We'll try to conjure up some appropriate images,
17 but the main focus of the room isn't the decor: it's the door leading to
18 the toilet -- and, perhaps, privacy?
25 Benny's café is populated with customers enjoying their lunch, so it
26 won't be a good place to change identities. However, the toilet to the
27 north looks promising, though Benny has strict rules about its use and
28 the door seems to be locked.
30 .. admonition:: Cultural Note
31 :class: admonition note
33 Not for the first time, this guide betrays its origins. In
34 European countries the word "toilet" often refers not only to the
35 white porcelain artefact, but also to the room in which it can be
36 found (also, a "bathroom" is for taking a bath, a "restroom" for
37 taking a rest). Bear with us on this; the dual usage becomes
38 important a little later on.
40 We define the café room in simple form:
42 .. code-block:: inform
44 Room cafe "Inside Benny's cafe"
46 "Benny's offers the FINEST selection of pastries and
47 sandwiches. Customers clog the counter, where Benny himself
48 manages to serve, cook and charge without missing a step. At
49 the north side of the cafe you can see a red door connecting
54 We'll elaborate on the last line (``n_to toilet_door``) later, when we
55 define the door object which lies between the café and the toilet.
57 We've mentioned a counter:
59 .. code-block:: inform
61 Appliance counter "counter" cafe
62 with name 'counter' 'bar',
65 "The counter is made of an astonishing ALLOY of metals,
66 STAIN-PROOF, SPILL-RESISTANT and VERY EASY to clean. Customers
67 enjoy their snacks with UTTER tranquillity, safe in the notion
68 that the counter can take it all.",
75 That ``before`` property, superficially normal, actually conceals a
76 little surprise. By now you should be entirely comfortable with using an
77 object's ``before`` property to intercept an action directed at that
78 object; for example, if the player types HIT COUNTER then the counter's
79 ``before`` property is potentially able to intercept the resulting
80 Attack action. However, the command PUT KEY ON COUNTER generates *two*
81 actions. First, a PutOn action is offered to the key (effectively
82 saying, do you want to be placed on top of the counter?); that’s the
83 normal bit. And then the surprise: a Receive action is offered to the
84 counter (effectively saying, are you happy to have the key placed on
85 you?) Both actions have the same opportunity of returning ``false`` to
86 let the action continue, ``true`` to prevent it.
90 There are a lot of actions here that are rendered in a typewriter font
91 and others that are not. Should these ones that are not be promoted
92 to having a typewriter font?
94 The Receive action is generated by the library in the PutOnSub action
95 handler, and also in InsertSub (so a command like PUT BIRD IN NEST sends a
96 Receive to the nest object). There’s a matching LetGo, generated by the
97 library from commands like TAKE KEY OFF COUNTER and REMOVE BIRD FROM
98 NEST. Receive and LetGo are examples of what’s called a :term:`fake
103 In "William Tell" we defined the ``quiver``, way back in
104 :ref:`possessions`, as an ``open container``. As things stand, the player
105 can put *any* held object, however inappropriate, into it. We could have
106 trapped the Receive action to ensure that arrows are the only acceptable
107 contents (recollect that ``~~``, to be read as "not", turns true into
108 false and vice versa):
110 .. code-block:: inform
114 print_ret "But it was a present from Hedwig, your wife.";
116 if (~~(noun ofclass Arrow))
117 print_ret "Only arrows -- clean arrows -- go in your quiver.";
120 Here, we intercept any attempt to place an item on the counter, and
121 translate it into an attempt to give that item to Benny. Part of the
122 game's plot depends on the player returning the toilet key to Benny, and
123 also paying him for his delicious cup of world-famous Cappuccino.
124 Putting the key and the money on the counter is a reasonable alternative
125 way for the player to accomplish this.
127 We've also mentioned some customers. These are treated as NPCs, reacting
128 to our hero’s performance.
130 .. code-block:: inform
132 Object customers "customers" cafe
133 with name 'customers' 'people' 'customer' 'men' 'women',
135 if (costume has worn)
136 "Most seem to be concentrating on their food, but some do
137 look at you quite blatantly. Must be the MIND-BEFUDDLING
138 colours of your costume.";
140 "A group of HELPLESS and UNSUSPECTING mortals, the kind
141 Captain FATE swore to DEFEND the day his parents choked on a
142 DEVIOUS slice of RASPBERRY PIE.";
146 if (costume has worn)
147 "People seem to MISTRUST the look of your FABULOUS costume.";
149 "As John Covarth, you attract LESS interest than Benny's
152 "There's no telling what sorts of MUTANT bacteria these
153 STRANGERS may be carrying around.";
155 "Mindless massacre of civilians is the qualification for
156 VILLAINS. You are SUPPOSED to protect the likes of these
160 "These people don't appear to be of the cooperative sort.";
162 number_of_comments 0, ! for counting the customer comments
164 if (location ~= cafe) return;
165 if (self.number_of_comments == 0) {
166 self.number_of_comments = 1;
167 print "^Nearby customers glance at your costume with open
170 if (random(2) == 1) { ! do this 50% of the time
171 self.number_of_comments = self.number_of_comments + 1;
172 switch (self.number_of_comments) {
173 2: "^~Didn't know there was a circus in town,~ comments one
174 customer to another. ~Seems like the clowns have the
176 3: "^~These fashion designers don't know what to do to show
177 off,~ snorts a fat gentleman, looking your way. Those
178 within earshot try to conceal their smiles.";
179 4: "^~Must be carnival again,~ says a man to his wife, who
180 giggles, stealing a peek at you. ~Time sure flies.~";
181 5: "^~Bad thing about big towns~, comments someone to his
182 table companion, ~is you get the damnedest bugs coming
184 6: "^~I sure WISH I could go to work in my pyjamas,~ says a
185 girl in an office suit to some colleagues. ~It looks SO
187 default: StopDaemon(self);
191 has scenery animate pluralname;
193 Let's go step by step. Our hero enters the café dressed as John Covarth,
194 but will eventually manage to change clothes in the toilet, and he'll
195 have to cross back through the café to reach the street and win the
196 game. The customers' ``description`` takes into consideration which
197 outfit the player character is wearing.
199 In "William Tell" we’ve seen a brief manifestation of the ``life``
200 property, but here we'll extend it a little. As we explained, ``life``
201 lets you intercept those actions particular to animate objects. Here we
202 trap ``Attack`` and ``Kiss`` to offer some customised messages for these
203 actions when applied to the customers. Also, we avoid conversation by
204 intercepting ``Ask``, ``Tell`` and ``Answer`` in order just to produce a
205 message which depends on the player character's attire.
207 One other feature of ``animate`` objects is the possibility of giving
208 them orders: BILL, SHAKE THE SPEAR or ANNIE, GET YOUR GUN . These
209 actions are dealt with in the ``orders`` property and, as with the
210 ``life`` property, the embedded routine can become quite complex if you
211 want your NPCs to behave in an interesting way. In this case, we don't
212 need the customers to perform tasks for us, so instead we provide a
213 simple rejection message, just in case the player tries to order people
216 Which leaves us with the ``daemon`` bit. A daemon is a property normally
217 used to perform some timed or repetitive action without the need of the
218 player’s direct interaction; for example, machines which work by
219 themselves, animals that move on their own, or people going about their
220 business. More powerfully, a daemon may take notice of the player’s
221 decisions at a particular moment, allowing for some interactive
222 behaviour; this is, however, an advanced feature that we won't use in
223 this example. A daemon gets a chance of doing something at the end of
224 every turn, typically to (or with) the object to which it’s associated.
225 In our example, the daemon triggers some sneers and nasty comments from
226 the customers once our hero comes out of the toilet dressed in Captain
229 To code a daemon, you need to do three things:
231 #. First, define a daemon property in the object’s body; the value of
232 the property is always an embedded routine.
234 #. However, daemons do nothing until you activate them. This is easily
235 achieved with the call :samp:`StartDaemon({obj_id})`, which may happen
236 anywhere (if you want some object's daemon to be active from the
237 beginning of the game,you can make the call in your Initialise
240 #. Once the daemon has finished its mission (if ever) you may stop it
241 with the call :samp:`StopDaemon({obj_id})`.
243 How does our particular daemon work? The appearance of our hero in full
244 crime-fighting wear will make the customers stare at him and make snarky
245 remarks. This must happen in the café room – the place where the
246 customers are -- so we need to make certain that the daemon does
247 something interesting only while the player stays in the right place
248 (and hasn’t wandered, say, back into the toilet):
250 .. code-block:: inform
252 if (location ~= cafe) return;
254 So if the location is not the café room (remember ~= means "not equal
255 to"), return without doing anything else; on this turn, there’s nothing
256 for the daemon to do. We use a plain ``return`` statement because the
257 value returned from a daemon doesn’t matter.
259 We have defined a customised local property, ``number_of_comments``, to
260 control the sequence of customers' remarks. When the Captain enters the
261 café room from the toilet for the first time, the value of the property
262 should be zero, so the statement block under the test:
264 .. code-block:: inform
266 if (self.number_of_comments == 0) {
267 self.number_of_comments = 1;
268 print "^Nearby customers glance at your costume with open
272 will happen only this once. What we intend is to output the text "Nearby
273 customers..." right after the startling entrance of our hero, setting up
274 the scene for the comments which are about to happen. Since we assign a
275 value of 1 to the property, the message will not be printed again.
276 Notice how we use an explicit ``print`` statement; the execution of the
277 daemon will continue normally to the next line.
279 We want the customers to indulge in witticisms once they see the
280 costumed Captain, but not on a completely predictable basis.
282 .. code-block:: inform
284 if (random(2) == 1) ...
286 ``random`` is an Inform routine used to generate random numbers or to
287 choose randomly between given choices; in the form
288 :samp:`random({expression})` it returns a random number between 1 and
289 ``expression`` inclusive. So our condition is actually stating: if a
290 random choice between 1 and 2 happens to be 1 then perform some action.
291 Remember that a daemon is run once at the end of every turn, so the
292 condition is trying to squeeze a comment from a customer roughly once
295 Next, we proceed as we have already seen in "William Tell", with a
296 switch statement to order the comments in a controlled sequence by
297 cunning use of our tailored local property, ``number_of_comments``. We
298 have written just five messages (could have been one or a hundred) and
299 then we reach the default case, which is a good place to stop the
300 daemon, since we have no more customers’ remarks to display.
302 Ah, but when does the daemon *start* functioning? Well, as soon as our
303 protagonist comes out of the toilet dressed in his multicoloured
304 super-hero pyjamas. Since we want to minimise the possible game states,
305 we’ll make some general rules to avoid trouble: (a) players will be able
306 to change only in the toilet; (b) we won’t let players change back into
307 street clothes; and (c) once players manage to step into the street thus
308 dressed, the game is won. So, we can safely assume that if players enter
309 the café in their Captain’s outfit, they’ll be coming from the toilet.
310 As a consequence of all this, we add an ``after`` property to the café
313 .. code-block:: inform
315 Room cafe "Inside Benny's cafe"
317 first_time_out false, ! Captain Fate's first appearance?
319 Go: ! The player has just arrived. Did he come from the toilet?
320 if (noun ~= s_obj) return false;
321 if (costume has worn && self.first_time_out == false) {
322 self.first_time_out = true;
323 StartDaemon(customers);
329 There are two useful techniques to detect when the player is entering or
330 leaving a room. We'll later see in detail how to deal with a player
331 trying to go away and how to avoid it if need be. For now, let’s just
332 mention that, in both cases, you have to intercept the ``Go`` action in
333 a room object; if you trap it in a ``before`` property, you’re checking
334 for departure from the room; if you trap it in an ``after`` property,
335 you’re checking for arrivals into the room. Right now we wish to know if
336 the player just came from the toilet, so we use an ``after`` property.
340 .. code-block:: inform
342 if (noun ~= s_obj) return false;
344 is telling the interpreter that we want to do something if the player
345 entered the room by typing a GO SOUTH command (this would normally mean
346 "coming from the north", but remember that nothing stops you from
347 connecting rooms without cardinal logic); the interpreter will apply
348 normal rules for the other available directions.
350 Then we check whether the player character is wearing the costume, in
351 which case it starts the ``daemon`` of the ``customers`` object. The use
352 of the local ``first_time_out`` property ensures that the condition is
353 ``true`` only once, so the statement block attached to it runs also
356 We've finished with the customers in the café. Now, we have the toilet
357 to the north which, for reasons of gameplay *and* decency, is protected
363 Door objects require some specific properties and attributes. Let's
364 first code a simple door:
366 .. code-block:: inform
368 Object toilet_door "toilet door" cafe
369 name name 'red' 'toilet' 'door',
371 "A red door with the unequivocal black man-woman
372 silhouettes marking the entrance to hygienic facilities.
373 There is a scribbled note stuck on its surface.",
377 has scenery door openable lockable locked;
379 We find this door in the café. We must specify the direction in which
380 the door leads and, as we have mentioned in the café's description, that
381 would be to the north. That’s what the ``door_dir`` property is for, and
382 in this case it takes the value of the north direction property
383 ``n_to``. Then we must tell Inform the identity of the room to be found
384 behind the door, hence the ``door_to`` property, which takes the value
385 of the toilet room -- to be defined later. Remember the café's
386 connection to the north, ``n_to toilet_door``? Thanks to it, Inform will
387 know that the door is in the way, and thanks to the ``door_to``
388 property, what lies beyond.
390 Doors *must* have the attribute ``door``, but beyond that we have a
391 stock of options to help us define exactly what kind of door we are
392 dealing with. As for containers, doors can be ``openable`` (which
393 activates the verbs OPEN and CLOSE so that they can be applied to this
394 object) and, since by default they are closed, you can give them the
395 attribute ``open`` if you wish otherwise. Additionally, doors can be
396 ``lockable`` (which sets up the LOCK/UNLOCK verbs) and you can make them
397 ``locked`` to override their default unlocked status. The verbs LOCK
398 and UNLOCK are expecting some kind of key object to operate the door.
399 This must be defined using the ``with_key`` property, whose value should
400 be the internal ID of the key; in our example, the soon-to-be-defined
401 ``toilet_key`` . If you don't supply this property, players won't be
402 able to lock or unlock the door.
404 This simple door definition has one problem, namely, that it exists only
405 in the café room. If you wish the door to be present also from the
406 toilet side, you can either (a) define another door to be found in the
407 ``toilet room``, or (b) make this one a two-sided door.
409 Solution (a) seems superficially straightforward, but then you have the
410 problem of keeping the states of the two doors – open/closed,
411 locked/unlocked -- in synch. In this scenario, where you can access the
412 toilet only through this door, that wouldn't be too complicated, since
413 you could leave the door object in the café room opened all the time,
414 regardless of what players do with the door object in the toilet room
415 and vice versa -- they are never going to see them at the same time. In
416 general terms, though, such inconsistencies lead to problems; solution
417 (a) is best ignored for most purposes.
419 Solution (b) is better, since you have only one door object to deal with
420 and its possible states affect both sides. However, the coding gets a
421 little bit complicated and you''ll have to define routines for most
424 .. code-block:: inform
426 Object toilet_door "toilet door"
427 with name 'red' 'toilet' 'door',
429 if (location == cafe)
430 "A red door with the unequivocal black man-woman silhouettes
431 marking the entrance to hygienic facilities. There is a
432 scribbled note stuck on its surface.";
434 "A red door with no OUTSTANDING features.";
436 found_in cafe toilet,
438 if (location == cafe) return n_to;
442 if (location == cafe) return toilet;
446 has scenery door openable lockable locked;
448 First of all, the door now needs a ``found_in`` property, since it's
449 going to be located both in the café and the toilet. The ``description``
450 checks which side of the door we are looking at – testing the current
451 value of the variable ``location``, which holds the room the player is
452 in -- because we have a scribbled note stuck on one side, but not on the
453 other. And the ``door_dir`` and ``door_to`` properties must use the same
454 trick, because we travel north from the café into the toilet, but south
455 from the toilet into the café.
457 Right now, the game will display "the toilet door" every time it needs
458 to refer to this object. It would be nice if we could somehow get the
459 game to distinguish between "the door to the toilet" and "the door to
460 the cafe", depending on the side we are facing. For this, a ``short_name
461 property`` is the thing. We have already talked about the external name
462 defined as part of an object's header information:
464 .. code-block:: inform
466 Object toilet_door "toilet door"
468 That ``toilet door`` will be the name displayed by the game at run-time
469 to refer to the door. With identical effect, this could also have been
472 .. code-block:: inform
475 with short_name "toilet door",
477 ``short_name`` is a property that supplies the external name of an
478 object, either as a string or an embedded routine. Normally, objects
479 retain the same external name throughout the game -- and the header
480 information method is perfect in that case -- but if it needs to change,
481 it's easy to write a routine as the value of ``short_name``:
483 .. code-block:: inform
486 with name 'red' 'toilet' 'door'
488 if (location == cafe) print "door to the toilet";
489 else print "door to the cafe";
495 Notice the ``return true`` at the end of the routine. You''ll recall
496 that the standard rule says "return false to carry on, true to take over
497 and stop normal execution”. In the case of ``short_name``, "carry on"
498 means "and now display the external name from the header information",
499 which is sometimes handy; for instance, you could write a ``short_name``
500 routine to prefix an object's external name with one of a range of
501 adjectives -- perhaps a shining/flickering/fading/useless lantern.
505 What's displayed if there isn't an external name in an object's header?
506 If you've read the section :ref:`compile-as-you-go`, you'll recall that
507 the interpreter simply uses the internal identifier within parentheses;
508 that is, with no external name and no ``short_name`` property, we might
511 You open the (toilet_door).
513 And the same principle applies if we were mistakenly to ``return
514 false`` from this short_name routine: we would get, first, the result
515 of our ``print`` statement, and then the standard rules would display
518 You open the door to the toilet(toilet_door).
520 Doors can get more complicated than this (no, please, don't throw our
521 guide out of the window). Here comes some optional deluxe coding to make
522 the door object a bit friendlier in game play, so you can skip it if you
525 Our door now behaves nicely at run-time. It can be locked and unlocked
526 if the player character has the right key; it can be opened and closed.
527 A sequence of commands to go into the toilet and lock the door behind
528 you would be: UNLOCK DOOR WITH KEY, OPEN DOOR, GO NORTH, CLOSE DOOR,
529 LOCK DOOR WITH KEY. After we are finished, let's go back to the café:
530 UNLOCK DOOR WITH KEY, OPEN DOOR, SOUTH. If the player is of the
531 fastidious kind: CLOSE DOOR, LOCK DOOR WITH KEY. This game features only
532 one door, but if it had three or four of them, players would grow
533 restless (at the very least) if they needed to type so many commands
534 just to go through a door. This is the kind of thing reportedly
535 considered as poor design, because the game is suddenly slowed down to
536 get over a simple action which involves no secrets or surprises. How
537 exciting can the crossing of an ordinary door be, after all?
539 If a few lines of code can make the life of the player easier, it's
540 worth a shot. Let's provide a few improvements to our toilet door in
541 ``before`` and ``after`` properties:
543 .. code-block:: inform
547 if (self hasnt locked || toilet_key notin player)
549 ks = keep_silent; keep_silent = true;
550 <Unlock self toilet_key>; keep_silent = ks;
553 if (self hasnt open) return false;
554 print "(first closing ", (the) self, ")^";
555 ks = keep_silent; keep_silent = true;
556 <Close self>; keep_silent = ks;
561 if (self has locked) return false;
562 print "You unlock ", (the) self, " and open it.^";
563 ks = keep_silent; keep_silent = true;
564 <Open self>; keep_silent = ks;
568 The basic idea here is to let the player who holds the key perform just
569 one action to both unlock *and* open the door (and, conversely, to close
570 *and* lock it). The relevant actions are ``Unlock`` and ``Open``, and
571 ``Lock`` ( ``Close`` is not necessary; if players just close the door we
572 shouldn’t assume that they want to lock it as well).
574 * **Open**: if the door isn't locked or the player doesn't hold the key,
575 keep going with the default ``Open`` action defined by the library.
576 That leaves a locked door and a player holding the key, so we
577 redirect processing to the ``Unlock`` action, giving as arguments the
578 door (self) and the toilet key. Since we are using single
579 angle-brackets ``<...>``, the action resumes after the unlocking is
580 done (note that the ``Unlock`` action also takes care of opening the
581 door). Finally, we ``return true`` to stop the library from trying to
582 open the door by itself.
584 * **Lock**: if the door is already closed, keep going with the standard
585 library ``Lock`` action. If not, tell players that we are closing the
586 door for them, redirect the action briefly to actually close it, and
587 then ``return false`` to let the ``Lock`` action proceed as before.
589 * **Unlock**: we place this action in the after property, so (let's
590 hope) the ``Unlock`` action has already happened. If the door is still
591 locked, something went wrong, so we ``return false`` to display the
592 standard message for an unsuccessful unlocking. Otherwise, the door is
593 now unlocked, so we inform the player that we are opening the door and
594 redirect the action to actually open it, returning ``true`` to
595 suppress the standard message.
597 In all processes there is a library variable called ``keep_silent``,
598 which can be either ``false`` (the normal state) or ``true``; when
599 ``true``, the interpreter does not display the associated message of an
600 action in progress, so we can avoid things like:
602 .. code-block:: transcript
605 You open the door to the toilet.
606 You unlock the door to the toilet and open it.
608 Although we want to set ``keep_silent`` to ``true`` for the duration of
609 our extra processing, we need to reset it afterwards. In a case like
610 this, good design practice is to preserve its initial value (which was
611 probably ``false``, but you should avoid risky assumptions); we use a
612 local variable ``ks`` to remember that initial setting so that we can
613 safely restore it afterwards. You’ll remember that a local variable in a
614 standalone routine is declared between the routine’s name and the
617 .. code-block:: inform
619 [ BeenToBefore this_room;
621 In exactly the same way, a local variable in an embedded routine is
622 declared between the ``[`` starting marker of the routine and the
625 .. code-block:: inform
629 You can declare up to fifteen variables this way -- just separated by
630 spaces -- which are usable only within the embedded routine. When we
633 .. code-block:: inform
637 we are actually making ``ks`` equal to whatever value ``keep_silent``
638 has (either ``true`` or ``false``; we actually don't care). We then set
639 ``keep_silent`` to ``true``, make the desired silent actions, and we
642 .. code-block:: inform
646 which restores the value originally stored in ``ks`` to ``keep_silent``.
647 The effect is that we manage to leave it as it was before we tampered
650 Well, that's about everything about doors. Everything? Well, no, not
651 really; any object can grow as complex as your imagination allows, but
652 we’ll drop the subject here. If you care to see more sophisticated doors,
653 check Exercises :dm4:`3 and 4 <s6.html#ex3>` in the |DM4|, where an
654 obliging door opens and unlocks by itself if the player simply walks in its
657 So far, we have the player in front of a locked door leading to the
658 toilet. A dead end? No, the description mentions a scribbled note on its
659 surface. This one should offer no problem:
661 .. code-block:: inform
663 Object "scribbled note" cafe
664 with name 'scribbled' 'note',
666 if (self.read_once == false) {
667 self.read_once = true;
668 "You apply your ENHANCED ULTRAFREQUENCY vision to the note
669 and squint in concentration, giving up only when you see the
670 borders of the note begin to blacken under the incredible
671 intensity of your burning stare. You reflect once more how
672 helpful it would've been if you'd ever learnt to read.
673 ^^A kind old lady passes by and explains:
674 ~You have to ask Benny for the key, at the counter.~^^
675 You turn quickly and begin, ~Oh, I KNOW that, but...~^^
676 ~My pleasure, son,~ says the lady, as she exits the cafe.";
679 "The scorched undecipherable note holds no SECRETS from
682 read_once false, ! has the player read the note once?
685 "No reason to start collecting UNDECIPHERABLE notes.";
689 Just notice how we change the description after the first time the
690 player examines the note, using the local property ``read_once`` created
691 just for this purpose. We don’t want the player to walk off with the
692 note, so we intercept the ``Take`` action and display something more in
693 character than the default message for scenery objects: "That's hardly
696 We've talked a lot about the toilet key; it seems about time to code it.
697 Originally, the key is in Benny's possession, and the player will have
698 to ask for it, just as the note explains. Although we'll define Benny in
699 detail throughout the next chapter, here we present a basic definition,
700 largely so that the key has a parent object.
702 .. code-block:: inform
704 Object benny "Benny" cafe
707 "A deceptively FAT man of uncanny agility, Benny entertains his
708 customers crushing coconuts against his forehead when the mood
710 has scenery animate male proper transparent;
712 Object toilet_key "toilet key" benny
713 with name 'toilet' 'key',
716 if (clothes has worn) print "the CRUCIAL key";
717 else print "the used and IRRELEVANT key";
721 "Your SUPRA PERCEPTIVE senses detect nothing of consequence
722 about the toilet key.",
725 "You SCAN your surroundings with ENHANCED AWARENESS,
726 but fail to detect any key.";
728 "Benny is trusting you to look after that key.";
731 While Benny has the key, there's logically no way to examine it (or
732 perform any other action involving it), but we want to prevent the
733 interpreter from objecting that ``You can't see any such thing``. We've
734 made the ``toilet_key`` a child of the ``benny`` object, and you can see
735 that Benny's got a ``transparent`` attribute; this means that the key is
736 in scope, and enables the player to refer to it without the interpreter
737 complaining. Because Benny also has an ``animate`` attribute, the
738 interpreter would normally intercept a TAKE KEY action with "That seems
739 to belong to Benny"; however, the same wouldn't apply to other commands
740 like TOUCH KEY and TASTE KEY . So, to prevent any interaction with the
741 key while it’s in Benny’s pockets, we define a ``before`` property.
743 .. code-block:: inform
747 "You SCAN your surroundings with ENHANCED AWARENESS,
748 but fail to detect any key.";
750 "Benny is trusting you to look after that key.";
753 All of the ``before`` properties that we've so far created have contained
754 one or more labels specifying the actions which they are to intercept;
755 you'll remember that in "William Tell" we introduced the ``default`` action
756 (see :ref:`props-class`) to mean "any value not already catered
757 for". There's one of those labels here, for the Drop action, but that's
758 preceded by a piece of code that will be executed at the start of *every*
759 action directed at the key. If it’s still in Benny’s possession, we display
760 a polite refusal; if the player has it then we prevent careless disposal;
761 otherwise, the action continues unhindered.
763 (In fact, the hat-on-a-pole ``Prop`` introduced in :ref:`south-side` had
764 this all-exclusive ``before`` property:
766 .. code-block:: inform
770 print_ret "You're too far away at the moment.";
773 It would have behaved exactly the same if we'd omitted the ``default``
774 label, as we do here for Benny's key.)
776 Another small innovation here: the ``invent`` library property (we
777 didn’t make it up) which enables you to control how objects appear in
778 inventory listings, overriding the default. Left to itself, the
779 interpreter simply displays the object’s external name, preceded either
780 by a standard article like "a" or "some", or one specifically defined in
781 the object's ``article`` property. Here we replace "the toilet key" with
782 one of two more helpful descriptions, making it a most valuable object
783 in the eyes of John Covarth, and something to be despised haughtily by
784 Captain Fate once it's of no further use to him.
786 When we had players in the street, we faced the problem that they might
787 choose to examine the café from the outside. While it's unlikely that
788 they'll try to examine the toilet room from the outside, it takes very
789 little effort to offer a sensible output just in case:
791 .. code-block:: inform
793 Object outside_of_toilet "toilet" cafe
794 with name 'toilet' 'bath' 'rest' 'room' 'bathroom' 'restroom',
797 if (toilet_door has open) {
802 "Your SUPERB deductive mind detects that the DOOR is
805 if (toilet_door has open)
806 "A brilliant thought flashes through your SUPERLATIVE
807 brain: detailed examination of the toilet would be
808 EXTREMELY facilitated if you entered it.";
810 "With a TREMENDOUS effort of will, you summon your
811 unfathomable ASTRAL VISION and project it FORWARD
812 towards the closed door... until you remember that it's
813 Dr Mystere who's the one with mystic powers.";
815 <<Open toilet_door>>;
817 <<Close toilet_door>>;
819 "That would be PART of the building.";
821 has scenery openable enterable;
823 As with the ``outside_of_cafe`` object, we intercept an ``Enter``
824 action, to teleport players into the toilet room if they type ENTER
825 TOILET (or to display a refusal if the toilet door is closed). Players
826 may try to EXAMINE TOILET; they'll get a different message if the door
827 is open -- we invite them to enter it -- or if it's closed. OPEN TOILET
828 and CLOSE TOILET inputs are redirected to ``Open`` and ``Close`` actions
829 for the toilet door; remember that the double angle-brackets imply a
830 ``return true``, so that the action stops there and the interpreter does
831 not attempt to ``Open`` or ``Close`` the ``outside_of_toilet`` object
832 itself after it has dealt with the door.
834 You're right: the toilet looms large in this game (we blame it on early
835 maternal influences). We’ve introduced an ambiguity problem with the
836 ``outside_of_toilet`` object, and we'll need some help in fixing it.