Appendix C – “William Tell” story¶
illiam Tell, our second game, is also very straightforward. See William Tell: a tale is born, William Tell: the early years, William Tell: in his prime and William Tell: the end is nigh.
Transcript of play¶
The place: Altdorf, in the Swiss canton of Uri. The year is 1307, at
which time Switzerland is under rule by the Emperor Albert of Habsburg.
His local governor -- the vogt -- is the bullying Hermann Gessler, who
has placed his hat atop a wooden pole in the centre of the town square;
everybody who passes through the square must bow to this hated symbol of
imperial might.
You have come from your cottage high in the mountains, accompanied by
your younger son, to purchase provisions. You are a proud and
independent man, a hunter and guide, renowned both for your skill as an
archer and, perhaps unwisely (for his soldiers are everywhere), for
failing to hide your dislike of the vogt.
It's market-day: the town is packed with people from the surrounding
villages and settlements.
William Tell
A simple Inform example
by Roger Firth and Sonja Kesserich.
Release 3 / Serial number 040804 / Inform v6.30 Library 6/11 SD
A street in Altdorf
The narrow street runs north towards the town square. Local folk are
pouring into the town through the gate to the south, shouting greetings,
offering produce for sale, exchanging news, enquiring with exaggerated
disbelief about the prices of the goods displayed by merchants whose
stalls make progress even more difficult.
"Stay close to me, son," you say, "or you'll get lost among all these
people."
>EXAMINE YOUR SON
A quiet, blond lad of eight summers, he's fast learning the ways of
mountain folk.
>GO NORTH
Further along the street
People are still pushing and shoving their way from the southern gate
towards the town square, just a little further north. You recognise the
owner of a fruit and vegetable stall.
Helga pauses from sorting potatoes to give you a cheery wave.
"Hello, Wilhelm, it's a fine day for trade! Is this young Walter? My,
how he's grown. Here's an apple for him -- tell him to mind that scabby
part, but the rest's good enough. How's Frau Tell? Give her my best
wishes."
>INVENTORY
You are carrying:
an apple
a quiver (being worn)
three arrows
a bow
>TALK TO HELGA
You warmly thank Helga for the apple.
[Your score has just gone up by one point.]
>GIVE THE APPLE TO WALTER
"Thank you, Papa."
[Your score has just gone up by one point.]
>NORTH
South side of the square
The narrow street to the south has opened onto the town square, and
resumes at the far side of this cobbled meeting place. To continue along
the street towards your destination -- Johansson's tannery -- you must
walk north across the square, in the middle of which you see Gessler's
hat set on that loathsome pole. If you go on, there's no way you can
avoid passing it. Imperial soldiers jostle rudely through the throng,
pushing, kicking and swearing loudly.
>EXAMINE THE SOLDIERS
They're uncouth, violent men, not from around here.
>EXAMINE HAT
You're too far away at the moment.
>N
Middle of the square
There is less of a crush in the middle of the square; most people prefer
to keep as far away as possible from the pole which towers here, topped
with that absurd ceremonial hat. A group of soldiers stands nearby,
watching everyone who passes.
>X HAT
The pole, the trunk of a small pine some few inches in diameter, stands
about nine or ten feet high. Set carefully on top is Gessler's ludicrous
black and red leather hat, with a widely curving brim and a cluster of
dyed goose feathers.
>N
A soldier bars your way.
"Oi, you, lofty; forgot yer manners, didn't you? How's about a nice
salute for the vogt's hat?"
>N
"I know you, Tell, yer a troublemaker, ain't you? Well, we don't want no
bovver here, so just be a good boy and salute the friggin' hat. Do it
now: I ain't gonna ask you again..."
>N
"OK, Herr Tell, now you're in real trouble. I asked you nice, but you
was too proud and too stupid. I think it's time that the vogt had a
little word with you."
And with that the soldiers seize you and Walter and, while the sergeant
hurries off to fetch Gessler, the rest drag you roughly towards the old
lime tree growing in the marketplace.
Marketplace near the square
Altdorf's marketplace, close by the town square, has been hastily
cleared of stalls. A troop of soldiers has pushed back the crowd to
leave a clear space in front of the lime tree, which has been growing
here for as long as anybody can remember. Usually it provides shade for
the old men of the town, who gather below to gossip, watch the girls,
and play cards. Today, though, it stands alone... apart, that is, from
Walter, who has been lashed to the trunk. About forty yards away, you
are restrained by two of the vogt's men.
Gessler is watching from a safe distance, a sneer on his face.
"It appears that you need to be taught a lesson, fool. Nobody shall pass
through the square without paying homage to His Imperial Highness
Albert; nobody, hear me? I could have you beheaded for treason, but I'm
going to be lenient. If you should be so foolish again, you can expect
no mercy, but this time, I'll let you go free... just as soon as you
demonstrate your archery skills by hitting this apple from where you
stand. That shouldn't prove too difficult; here, sergeant, catch.
Balance it on the little bastard's head."
>X GESSLER
Short, stout but with a thin, mean face, Gessler relishes the power he
holds over the local community.
>X WALTER
He stares at you, trying to appear brave and remain still. His arms are
pulled back and tied behind the trunk, and the apple nestles amid his
blond hair.
>X APPLE
At this distance you can barely see it.
>SHOOT THE APPLE
Slowly and steadily, you place an arrow in the bow, draw back the
string, and take aim with more care than ever in your life. Holding your
breath, unblinking, fearful, you release the arrow. It flies across the
square towards your son, and drives the apple against the trunk of the
tree. The crowd erupts with joy; Gessler looks distinctly disappointed.
*** You have won ***
In that game you scored 3 out of a possible 3, in 17 turns.
Would you like to RESTART, RESTORE a saved game or QUIT?
> QUIT
Game source code¶
!% -SD
!============================================================================
Constant Story "William Tell";
Constant Headline
"^A simple Inform example
^by Roger Firth and Sonja Kesserich.^";
!Release 1; Serial "020428"; ! IBG first edition (public beta)
!Release 2; Serial "020827"; ! IBG second edition
Release 3; Serial "040804"; ! for keeping track of public releases
Constant MAX_SCORE = 3;
Include "Parser";
Include "VerbLib";
!============================================================================
! Object classes
Class Room
has light;
Class Prop
with before [;
Examine:
return false;
default:
print_ret "You don't need to worry about ", (the) self, ".";
],
has scenery;
Class Furniture
with before [;
Take,Pull,Push,PushDir:
print_ret (The) self, " is too heavy for that.";
],
has static supporter;
Class Arrow
with name 'arrow' 'arrows//p',
article "an",
plural "arrows",
description "Just like all your other arrows -- sharp and true.",
before [;
Drop,Give,ThrowAt:
print_ret "Your arrows are sharp, and you guard them carefully.";
];
Class NPC
with life [;
Answer,Ask,Order,Tell:
print_ret "Just use T[ALK] [TO ", (the) self, "].";
],
has animate;
!============================================================================
! The game objects
Room street "A street in Altdorf"
with description [;
print "The narrow street runs north towards the town square.
Local folk are pouring into the town through the gate to the
south, shouting greetings, offering produce for sale,
exchanging news, enquiring with exaggerated disbelief about
the prices of the goods displayed by merchants whose stalls
make progress even more difficult.^";
if (self hasnt visited)
print "^~Stay close to me, son,~ you say,
~or you'll get lost among all these people.~^";
],
n_to below_square,
s_to
"The crowd, pressing north towards the square,
makes that impossible.";
Prop "south gate" street
with name 'south' 'southern' 'wooden' 'gate',
description "The large wooden gate in the town walls is wide open.";
Prop "assorted stalls"
with name 'assorted' 'stalls',
description "Food, clothing, mountain gear; the usual stuff.",
found_in street below_square,
has pluralname;
Prop "produce" !! added
with name 'goods' 'produce' 'food' 'clothing' 'mountain' 'gear' 'stuff',
description "Nothing special catches your eye.",
found_in street below_square,
has pluralname;
Prop "merchants"
with name 'merchant' 'merchants' 'trader' 'traders',
description
"A few crooks, but mostly decent traders touting their wares
with raucous overstatement.",
found_in street below_square,
has animate pluralname;
Prop "local people"
with name 'people' 'folk' 'local' 'crowd',
description "Mountain folk, just like yourself.",
found_in [; return true; ],
has animate pluralname;
!----------------------------------------------------------------------------
Room below_square "Further along the street"
with description
"People are still pushing and shoving their way from the southern
gate towards the town square, just a little further north.
You recognise the owner of a fruit and vegetable stall.",
n_to south_square,
s_to street;
Furniture stall "fruit and vegetable stall" below_square
with name 'fruit' 'veg' 'vegetable' 'stall' 'table',
description
"It's really only a small table, with a big heap of potatoes,
some carrots and turnips, and a few apples.",
before [;
Search:
<<Examine self>>;
],
has scenery;
Prop "potatoes" below_square
with name 'potato' 'potatoes' 'spuds',
description
"Must be a particularly early variety... by some 300 years!",
has pluralname;
Prop "fruit and vegetables" below_square
with name 'carrot' 'carrots' 'turnip' 'turnips' 'apples' 'vegetables',
description "Fine locally grown produce.",
has pluralname;
NPC stallholder "Helga" below_square
with name 'stallholder' 'greengrocer' 'monger' 'shopkeeper' 'merchant'
'owner' 'Helga' 'dress' 'scarf' 'headscarf',
description
"Helga is a plump, cheerful woman,
concealed beneath a shapeless dress and a spotted headscarf.",
initial [;
print "Helga pauses from sorting potatoes
to give you a cheery wave.^";
if (location hasnt visited) {
move apple to player;
print "^~Hello, Wilhelm, it's a fine day for trade! Is this
young Walter? My, how he's grown. Here's an apple for him
-- tell him to mind that scabby part, but the rest's good
enough. How's Frau Tell? Give her my best wishes.~^";
}
],
times_spoken_to 0, ! for counting the conversation topics
life [;
Kiss:
print_ret "~Ooh, you saucy thing!~";
Talk:
self.times_spoken_to = self.times_spoken_to + 1;
switch (self.times_spoken_to) {
1: score = score + 1;
print_ret "You warmly thank Helga for the apple.";
2: print_ret "~See you again soon.~";
default:
return false;
}
],
has female proper;
!----------------------------------------------------------------------------
Room south_square "South side of the square"
with description
"The narrow street to the south has opened onto the town square,
and resumes at the far side of this cobbled meeting place.
To continue along the street towards your destination --
Johansson's tannery -- you must walk north across the square,
in the middle of which you see Gessler's hat set on that
loathsome pole. If you go on, there's no way you can avoid
passing it. Imperial soldiers jostle rudely through the throng,
pushing, kicking and swearing loudly.",
n_to mid_square,
s_to below_square;
Prop "hat on a pole" !! changed
with name 'hat' 'pole',
before [;
default:
print_ret "You're too far away at the moment.";
],
found_in south_square north_square;
Prop "Gessler's soldiers"
with name 'soldier' 'soldiers' 'guard' 'guards', !! added
description "They're uncouth, violent men, not from around here.",
before [;
FireAt:
print_ret "You're outnumbered many times.";
Talk:
print_ret "Such scum are beneath your contempt.";
],
found_in south_square mid_square north_square marketplace,
has animate pluralname proper;
!----------------------------------------------------------------------------
Room mid_square "Middle of the square"
with description
"There is less of a crush in the middle of the square; most
people prefer to keep as far away as possible from the pole
which towers here, topped with that absurd ceremonial hat. A
group of soldiers stands nearby, watching everyone who passes.",
n_to north_square,
s_to south_square,
warnings_count 0, ! for counting the soldier's warnings
before [;
Go:
if (noun == s_obj) {
self.warnings_count = 0;
pole.has_been_saluted = false;
}
if (noun == n_obj) {
if (pole.has_been_saluted == true) {
print "^~Be sure to have a nice day.~^";
return false;
} ! end of (pole has_been_saluted)
else {
self.warnings_count = self.warnings_count + 1;
switch (self.warnings_count) {
1: print_ret "A soldier bars your way. ^^
~Oi, you, lofty; forgot yer manners, didn't you?
How's about a nice salute for the vogt's hat?~";
2: print_ret "^~I know you, Tell, yer a troublemaker,
ain't you? Well, we don't want no bovver here,
so just be a good boy and salute the friggin'
hat. Do it now: I ain't gonna ask you again...~";
default:
print "^~OK, ";
style underline; print "Herr"; style roman;
print " Tell, now you're in real trouble. I asked you
nice, but you was too proud and too stupid. I
think it's time that the vogt had a little word
with you.~
^^
And with that the soldiers seize you and Walter
and, while the sergeant hurries off to fetch
Gessler, the rest drag you roughly towards the
old lime tree growing in the marketplace.^";
move apple to son;
PlayerTo(marketplace);
return true;
} ! end of switch
} ! end of (pole has_NOT_been_saluted)
} ! end of (noun == n_obj)
];
Furniture pole "hat on a pole" mid_square !! changed
with name 'wooden' 'pole' 'pine' 'hat' 'black' 'red' 'brim' 'feathers',
description
"The pole, the trunk of a small pine some few inches in diameter,
stands about nine or ten feet high. Set carefully on top is
Gessler's ludicrous black and red leather hat, with a widely
curving brim and a cluster of dyed goose feathers.",
has_been_saluted false,
before [;
FireAt: !! added
print_ret "Tempting, but you're not looking for trouble.";
Salute:
self.has_been_saluted = true;
print_ret "You salute the hat on the pole. ^^
~Why, thank you, sir,~ sneers the soldier.";
],
has scenery;
!----------------------------------------------------------------------------
Room north_square "North side of the square"
with description
"A narrow street leads north from the cobbled square. In its
centre, a little way south, you catch a last glimpse of the pole
and hat.",
n_to [;
deadflag = 3;
print_ret "With Walter at your side, you leave the square by the
north street, heading for Johansson's tannery.";
],
s_to "You hardly feel like going through all that again.";
!----------------------------------------------------------------------------
Room marketplace "Marketplace near the square"
with description
"Altdorf's marketplace, close by the town square, has been hastily
cleared of stalls. A troop of soldiers has pushed back the crowd
to leave a clear space in front of the lime tree, which has been
growing here for as long as anybody can remember. Usually it
provides shade for the old men of the town, who gather below to
gossip, watch the girls, and play cards. Today, though, it
stands alone... apart, that is, from Walter, who has been lashed
to the trunk. About forty yards away, you are restrained by two
of the vogt's men.",
cant_go "What? And leave your son tied up here?";
Object tree "lime tree" marketplace
with name 'lime' 'tree',
description "It's just a large tree.",
before [;
FireAt:
if (BowOrArrow(second) == true) {
deadflag = 3;
print_ret "Your hand shakes a little, and your arrow flies
high, hitting the trunk a few inches above Walter's
head.";
}
return true;
],
has scenery;
NPC governor "governor" marketplace
with name 'governor' 'vogt' 'Hermann' 'Gessler',
description
"Short, stout but with a thin, mean face, Gessler relishes the
power he holds over the local community.",
initial [;
print "Gessler is watching from a safe distance,
a sneer on his face.^";
if (location hasnt visited)
print "^~It appears that you need to be taught a lesson,
fool. Nobody shall pass through the square without paying
homage to His Imperial Highness Albert; nobody, hear me?
I could have you beheaded for treason, but I'm going to
be lenient. If you should be so foolish again, you can
expect no mercy, but this time, I'll let you go free...
just as soon as you demonstrate your archery skills by
hitting this apple from where you stand. That shouldn't
prove too difficult; here, sergeant, catch. Balance it on
the little bastard's head.~^";
],
life [;
Talk:
print_ret "You cannot bring yourself to speak to him.";
],
before [;
FireAt:
if (BowOrArrow(second) == true) {
deadflag = 3;
print_ret "Before the startled soldiers can react, you turn
and fire at Gessler; your arrow pierces his heart,
and he dies messily. A gasp, and then a cheer,
goes up from the crowd.";
}
return true;
],
has male;
!============================================================================
! The player's possessions
Object bow "bow"
with name 'bow',
description "Your trusty yew bow, strung with flax.",
before [;
Drop,Give,ThrowAt:
print_ret "You're never without your trusty bow.";
]
has clothing;
Object quiver "quiver"
with name 'quiver',
description
"Made of goatskin, it usually hangs over your left shoulder.",
before [;
Drop,Give,ThrowAt:
print_ret "But it was a present from Hedwig, your wife.";
],
has container open clothing;
Arrow "arrow" quiver;
Arrow "arrow" quiver;
Arrow "arrow" quiver;
NPC son "your son"
with name 'son' 'your' 'boy' 'lad' 'Walter',
description [;
if (location == marketplace)
print_ret "He stares at you, trying to appear brave and
remain still. His arms are pulled back and tied behind
the trunk, and the apple nestles amid his blond hair.";
else
print_ret "A quiet, blond lad of eight summers, he's fast
learning the ways of mountain folk.";
],
life [;
Give:
score = score + 1;
move noun to self;
print_ret "~Thank you, Papa.~";
Talk:
if (location == marketplace)
print_ret "~Stay calm, my son, and trust in God.~";
else
print_ret "You point out a few interesting sights.";
],
before [;
Examine,Listen,Salute,Talk:
return false;
FireAt:
if (location == marketplace) {
if (BowOrArrow(second) == true) {
deadflag = 3;
print_ret "Oops! Surely you didn't mean to do that?";
}
return true;
}
else
return false;
default:
if (location == marketplace)
print_ret "Your guards won't permit it.";
else
return false;
],
found_in [; return true; ],
has male proper scenery transparent;
Object apple "apple"
with name 'apple',
description [;
if (location == marketplace)
print_ret "At this distance you can barely see it.";
else
print_ret "The apple is blotchy green and brown.";
],
before [;
Drop:
print_ret "An apple is worth quite a bit --
better hang on to it.";
Eat:
print_ret "Helga intended it for Walter...";
FireAt:
if (location == marketplace) {
if (BowOrArrow(second) == true) {
score = score + 1;
deadflag = 2;
print_ret "Slowly and steadily, you place an arrow in
the bow, draw back the string, and take aim with
more care than ever in your life. Holding your
breath, unblinking, fearful, you release the
arrow. It flies across the square towards your
son, and drives the apple against the trunk of
the tree. The crowd erupts with joy;
Gessler looks distinctly disappointed.";
}
return true;
}
else
return false;
];
!============================================================================
! Entry point routines
[ Initialise;
location = street;
lookmode = 2; ! like the VERBOSE command
move bow to player;
move quiver to player; give quiver worn;
player.description =
"You wear the traditional clothing of a Swiss mountaineer.";
print_ret "^^
The place: Altdorf, in the Swiss canton of Uri. The year is 1307,
at which time Switzerland is under rule by the Emperor Albert of
Habsburg. His local governor -- the vogt -- is the bullying
Hermann Gessler, who has placed his hat atop a wooden pole in
the centre of the town square; everybody who passes through the
square must bow to this hated symbol of imperial might.
^^
You have come from your cottage high in the mountains,
accompanied by your younger son, to purchase provisions. You are
a proud and independent man, a hunter and guide, renowned both
for your skill as an archer and, perhaps unwisely (for his soldiers
are everywhere), for failing to hide your dislike of the vogt.
^^
It's market-day: the town is packed with people from the
surrounding villages and settlements.^";
];
[ DeathMessage; print "You have screwed up a favourite folk story"; ];
!============================================================================
! Standard and extended grammar
Include "Grammar";
!----------------------------------------------------------------------------
[ TalkSub;
if (noun == player) print_ret "Nothing you hear surprises you.";
if (RunLife(noun,##Talk) ~= false) return; ! consult life[; Talk: ]
print_ret "At the moment, you can't think of anything to say.";
];
Verb 'talk' 't//' 'converse' 'chat' 'gossip'
* 'to'/'with' creature -> Talk
* creature -> Talk;
!----------------------------------------------------------------------------
[ BowOrArrow o;
if (o == bow or nothing || o ofclass Arrow) return true;
print "That's an unlikely weapon, isn't it?^";
return false;
];
[ FireAtSub;
if (noun == nothing)
print_ret "What, just fire off an arrow at random?";
if (BowOrArrow(second) == true)
print_ret "Unthinkable!";
];
Verb 'fire' 'shoot' 'aim'
* -> FireAt
* noun -> FireAt
* 'at' noun -> FireAt
* 'at' noun 'with' noun -> FireAt
* noun 'with' noun -> FireAt
* noun 'at' noun -> FireAt reverse;
Extend 'attack' replace
* noun -> FireAt;
!----------------------------------------------------------------------------
[ SaluteSub;
if (noun has animate) print_ret (The) noun, " acknowledges you.";
print_ret (The) noun, " takes no notice.";
];
Verb 'bow' 'nod' 'kowtow' 'genuflect'
* 'at'/'to'/'towards' noun -> Salute;
Verb 'salute' 'greet' 'acknowledge'
* noun -> Salute;
Extend 'give'
* 'homage' 'to' noun -> Salute;
Extend 'wave'
* 'at' noun -> Salute;
!----------------------------------------------------------------------------
[ UntieSub; print_ret "You really shouldn't try that."; ];
Verb 'untie' 'unfasten' 'unfix' 'free' 'release'
* noun -> Untie;
!============================================================================
Compile-as-you-go¶
Your understanding of how the “William Tell” game works will be
considerably enhanced if you type in the code for yourself as you read
through the guide. However, it takes us four chapters to describe the
game, which isn’t complete and playable until the end of Chapter 9. Even
if you make no mistakes in your typing, the game won’t compile without
errors before that point, because of references in earlier chapters to
objects which aren’t presented until later chapters (for example,
Chapter 6 mentions the bow and quiver objects, but we don’t
define them until Chapter 7). This is a bit of a nuisance, because as a
general rule we advise you to compile frequently – more or less after
every change you make to a game – in order to detect syntax and
spelling mistakes as soon as possible.
Fortunately, there’s a fairly easy way round the difficulty, though it involves a little bit of cheating. The trick is temporarily to add minimal definitions – often called “stubs” – of the objects whose full definitions have yet to be provided.
For example, if you try to compile the game in the state that it’s reached by the end of Chapter 6, you’ll get this:
Tell.inf(16): Warning: Class "Room" declared but not used
Tell.inf(19): Warning: Class "Prop" declared but not used
Tell.inf(27): Warning: Class "Furniture" declared but not used
Tell.inf(44): Error: No such constant as "street"
Tell.inf(46): Error: No such constant as "bow"
Tell.inf(47): Error: No such constant as "quiver"
Compiled with 3 errors and 3 warnings
However, by adding these lines to the end of your game file:
! ===============================================================
! TEMPORARY DEFINITIONS NEEDED TO COMPILE AT THE END OF CHAPTER 6
Room street;
Object bow;
Object quiver;
a compilation should now give only this:
Tell.inf(19): Warning: Class "Prop" declared but not used
Tell.inf(27): Warning: Class "Furniture" declared but not used
Compiled with 2 warnings
That’s a lot better. It’s not worth worrying about those warnings, since it’s easy to understand where they come from; anyway, they’ll go away shortly. More important, there are no errors, which means that you’ve probably not made any major typing mistakes. It also means that the compiler has created a story file, so you can try “playing” the game. If you do, though, you’ll get this:
William Tell
A simple Inform example
by Roger Firth and Sonja Kesserich.
Release 3 / Serial number 040804 / Inform v6.30 Library 6/11 SD
(street)
** Library error 11 (27,0) **
** The room "(street)" has no "description" property **
>
Whoops! We’ve fallen foul of Inform’s rule saying that every room must
have a description property, to be displayed by the interpreter when
you enter that room. Our street stub hasn’t got a description,
so although the game compiles successfully, it still causes an error to
be reported at run-time.
The best way round this is to extend the definition of our Room
class, thus:
Class Room
with description "UNDER CONSTRUCTION",
has light;
By doing this, we ensure that every room has a description of some
form; normally we’d override this default value with something
meaningful – “The narrow street runs north towards the town square...”
and so on – by including a description property in the object’s
definition. However, in a stub object used only for testing, a default
description is sufficient (and less trouble):
William Tell
A simple Inform example
by Roger Firth and Sonja Kesserich.
Release 3 / Serial number 040804 / Inform v6.30 Library 6/11 SD
(street)
UNDER CONSTRUCTION
>INVENTORY
You are carrying:
a (quiver) (being worn)
a (bow)
>EXAMINE QUIVER
You can't see any such thing.
>
You’ll notice a couple of interesting points. Because we didn’t supply
external names with our street , bow and quiver stubs, the
compiler has provided some for us – (street) , (bow) and
(quiver) – simply by adding parentheses around the internal IDs
which we used. And, because our bow and quiver stubs have no
name properties, we can’t actually refer to those objects when
playing the game. Neither of these points would be acceptable in a
finished game, but for testing purposes at this early stage – they’ll
do.
So far, we’ve seen how the addition of three temporary object
definitions enables us to compile the incomplete game, in its state at
the end of Chapter 6. But once we reach the end of Chapter 7, things
have moved on, and we now need a different set of stub objects. For a
test compilation at this point, remove the previous set of stubs, and
instead add these – south_square and apple objects, and a dummy
action handler to satisfy the Talk action in Helga’s life property:
! ===============================================================
! TEMPORARY DEFINITIONS NEEDED TO COMPILE AT THE END OF CHAPTER 7
Room south_square;
Object apple;
[ TalkSub; ];
Similarly, at the end of Chapter 8, replace the previous stubs by these if you wish to check that the game compiles:
! ===============================================================
! TEMPORARY DEFINITIONS NEEDED TO COMPILE AT THE END OF CHAPTER 8
Room marketplace;
Object apple;
NPC son;
[ TalkSub; ];
[ FireAtSub; ];
[ SaluteSub; ];
Finally, by the end of Chapter 9 the game is complete, so you can delete the stubs altogether.
Used with care, this technique of creating a few minimal stub objects can be convenient – it enables you to “sketch” a portion of your game in outline form, and to compile and test the game in that state, without needing to create complete object definitions. However, you’ve got very little interaction with your stubs, so don’t create too many of them. And of course, never forget to flesh out the stubs into full definitions as soon as you can.