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9 .. image:: /images/picD.png
16 uring our travels, we've encountered certain terms which have particular
17 significance in the context of the Inform text adventure development
18 system; here are brief definitions of many of those specialised words and
24 The generated effect of the player's input, usually by the `parser`
25 but also occasionally by the designer's code. It refers to a single
26 task to be processed by Inform, such as DROP KETTLE, and it's stored
27 in four numbers: one each for the action itself and the ``actor``
28 object who is to perform it (the player or an `NPC`), one for the
29 ``noun`` -- or direct object, if present -- and a fourth for the
30 ``second`` noun -- if it exists, for example the "POT" in THROW
31 KETTLE AT POT. See also `fake action`.
34 The testing which is carried out by the game's `designer`, in a
35 futile attempt to ensure that it does everything that it should and
36 nothing that it shouldn't. See also `beta-testing`.
39 A parameter supplied in a call to a `routine`, which is the actual
40 value for one of the routine's defined local variables. For
41 example, the argument is 8 in the call ``MyRoutine(8)``. The
42 definition of the routine includes the variable that will hold the
43 argument, in this case ``x``: ``[ MyRoutine x; ... ];``
49 A statement which sets or changes the value of a `variable`. There
50 are three in Inform: ``=`` (set equal to), ``++`` (add one to the
51 current value), ``--`` (subtract one from the current value).
54 Named flags that can be defined for an object after the keyword
55 ``has`` . An attribute is either present (on) or not present (off).
56 The designer may test from any other part of the program *if* an
57 object *has* a certain attribute, *give* an attribute to an object
58 or take it away as need arises. For instance, the attribute
59 ``container`` states that the object is capable of having other
60 objects placed inside it.
66 Information about a game which is displayed at the start of play.
69 The testing which is carried out by a small band of trusted
70 volunteers, prior to general public release, during which the gross
71 inadequacy of the designer's `alpha-testing` effort becomes
75 A computer file containing binary data -- 0s and 1s -- which is
76 created by a program and which only a program can understand.
79 Used to highlight a term explained in this glossary.
85 A special `object` template from which other objects can inherit
86 `properties` and/or `attributes`. The template must begin with the
87 word ``Class`` and must have an internal identifier. Objects that
88 wish to inherit from a class usually begin with the internal ID of
89 the class in place of the word ``Object`` , but may instead define a
90 segment ``class`` followed by the class's internal ID. The designer
91 may test whether an object belongs to -- is a member of -- a class.
94 See `statement block`.
97 Text which starts with an exclamation mark ``!`` and which is
98 ignored by the compiler when it reads the `source file`; added to
99 improve the file's layout or for explanatory notes.
102 The time when the `compiler` is at work making the `story file`.
106 A program that reads the source code written by the designer and
107 turns it into a `story file`, which can then be played by a
108 Z-machine `interpreter`.
111 A particular value which is defined at `compile-time`, always stays
112 the same and cannot be changed while the game is being played.
113 Common examples include numbers, strings and the internal IDs of
114 objects, any of which can be either written out explicitly or set as
115 the value of a named ``Constant``.
118 A option which causes to compiler to include extra code into the
119 story file, thus making it easier for the designer to understand
120 what's happening while a game is being tested prior to release. See
124 A person who uses Inform to create a text adventure game: in other
125 words, gentle reader, you.
128 The collection of all input words "understood" by the game.
131 A word written in single quotes '...' within the `source file`,
132 usually (but not exclusively) as one of the values assigned to an
133 object's ``name`` property. All such words are stored in the
134 `dictionary`, which is consulted by the `parser` when attempting to
135 make sense of a player's command. Only the first nine characters
136 are significant (thus ``'cardiogram'`` and ``'cardiograph'`` are
137 treated as the same word). Use ``'coins//p'`` to mark "``coins``"
138 as plural, referring to all coin objects which are present. Use
139 ``'t//'`` to enter the single-character word "t" into the dictionary
140 (``'t'`` is a constant representing a character value).
143 A line of Inform code which asks the `compiler` to do something
144 there and then, at `compile-time`; typical examples are to Include
145 the contents of another file, or to set aside some space within the
146 story file where a variable value may be stored. Not to be confused
147 with a `statement`, which asks the compiler to compose an
148 instruction which the interpreter will obey at `run-time`; typical
149 examples are to display some text, or to change the value held
150 within a variable's storage space.
153 A general-purpose program for creating and modifying `text file`\s.
156 A routine that is defined in the body of an object, as the value of
157 one of its `properties`. Unlike a `standalone routine`, an embedded
158 routine doesn't have a name of its own, and returns ``false`` if
159 execution reaches the terminating marker ``]``.
162 One of a predefined list of optional routines which, if you provide
163 it, will be called by the library either to produce some
164 supplementary output or to return a value causing the library to
165 change its default behaviour.
168 An action generated indirectly by the library rather than directly
169 by what the player types. For example, PUT X IN Y triggers a real
170 action of Insert (which can be intercepted by X) and a fake action
171 of Receive (which can be intercepted by Y).
174 A logical state which is the opposite of `true`, represented by the
178 A variable which can take only two possible values.
184 A variable not specific to any routine or object, which can be used
185 by any routine in the game.
188 The process by which an `object` belonging to a `class` acquires the
189 properties and attributes of said class. Inheritance happens
190 automatically; the designer has just to create class definitions,
191 followed by objects having those classes.
194 A program that reads the `story file` of a game and enables people
195 to play it. Interpreters must be platform-specific (that is, they
196 will be different programs for each operating system), thus allowing
197 the story file to be universal and platform-independent.
200 Used for emphasis, and as a placeholder to represent a value which
204 A group of text files, part of the Inform system, that includes the
205 `parser`, definitions for the `model world`, language files, grammar
206 definitions and a customised stock of default answers and behaviour
207 for the player's actions. The library will make frequent calls to
208 the game file to see if the designer wants to override those
212 The actual files containing the source code of the library. There
213 are basically three (although these three Include other files as
214 well): ``parser.h`` , ``verblib.h`` and ``grammar.h``, and they
215 should be Included in every Inform game.
218 One of a set of routines included as part of the library which the
219 designer can call to perform some commonly useful task.
222 A variable which is part of only one `routine`; its value remains
223 unavailable to other routines in the game. The value of a local
224 variable is *not* preserved between calls to the routine.
227 The imaginary environment which the player character inhabits.
230 The ASCII control character(s) used to mark the end of a line of
234 A non-player character; any character other than the protagonist.
235 Could range from an opponent or love interest to a pet gerbil or a
239 A group of `routine`\s and variables bundled up together in a
240 coherent unit. Objects represent the items that make up the `model
241 world` (a torch; a car; a beam of light; etc.), a fact which
242 organises the designer's code in sensible chunks, easy to manage.
243 Each object has two parts: the header, which comprises the internal
244 ID, the external name and its defined parent (all fields are
245 optional), and the body, which comprises the property variables and
246 attribute flags particular to that object, if any.
249 A hierarchy that defines objects' relationships in terms of
250 containment. Each `object` is either contained within another
251 object -- its parent -- or is *not* contained; objects such as rooms
252 which are not within another object have the constant
253 ``nothing`` (0) as a parent. An object contained within another is
254 a child. For example, a shoe inside a box: the box is the shoe's
255 parent and the shoe is a child of the box. Consider now this box
256 being inside the wardrobe. The box is a child of the wardrobe, but
257 the shoe is still a child of the box, not the wardrobe. In a normal
258 game, the object tree will undergo many transformations as the
259 result of the player's activities.
265 Part of the `library` which is responsible for analysing the
266 player's input and trying to make sense of it, dividing it into
267 separate words (verb, nouns) and trying to match them against the
268 words stored in the game's `dictionary` and the actions defined in
269 the game's grammar. If the player's input makes sense, the parser
270 will trigger the resulting `action`; if not, it will complain that
271 it didn't understand.
274 1. a personal computer;
275 2. the player character (see `player`).
278 1. the final user of the game, normally a person full of radical
279 opinions about your capabilities as a designer;
280 2. a variable referring to the `object` -- sometimes known as an
281 "avatar" -- which currently represents that user within the
285 A customised rule to apply while in a ``print`` or ``print_ret``
286 statement, to control the manner in which an item of data is to be
287 displayed. For example: ``print (The) noun, " is mine."`` is
288 telling the game to use a capitalised definite article for the noun.
289 The library defines a stock of print rules, and designers may create
293 Variables attached to a single `object`, of which they are a part.
294 They are defined in the body of the object after the keyword
295 ``with`` and have a name and a value. The latter (which defaults
296 to 0) can be a number, a string "...", a dictionary word '...' or an
297 embedded routine ``[;...]``; it can also be a list of those
298 separated by spaces. The value of an object's property can be
299 tested and changed from any part of the game. The fact that an
300 object provides a property may be tested.
303 The :newsgroup:`rec.arts.int-fiction` Usenet newsgroup for IF
307 The :newsgroup:`rec.games.int-fiction` Usenet newsgroup for IF
311 An `object` which defines a geographical unit into which the map of
312 the `model world` is divided. Rooms have no parent object (or, more
313 precisely, their parent object is ``nothing``) and they represent
314 the places where the player character is at any given moment -- the
315 player character can't be in more than one room at a time. Note
316 that the name "room" does not imply necessarily "indoors". A
317 clearing, a sandy beach, the top of a tree, even floating in outer
318 space -- these are all possible room objects.
321 In general terms, a routine is a computer program that makes some
322 specific calculation, following an ordered set of instructions; this
323 is the only unit of coherent and executable code understood by
324 Inform. More practically, a routine is a collection of
325 `statement`\s which are written between markers ``[...]``. When a
326 routine is "called", possibly with arguments -- specific values for
327 its defined variables, if they exist -- the interpreter executes the
328 statements in sequence. If the interpreter encounters a ``return``
329 statement, or reaches the ``]`` at the end of the routine, it
330 immediately stops executing statements in the routine and resumes
331 execution at the statement which called that routine. Every routine
332 returns a value, which is either supplied by the return statement or
333 implied by the ] at the end of the routine. See `embedded routine`
334 and `standalone routine`.
337 The period of time when the `interpreter` is running a `story file`
338 (that is, someone is playing the game). See also `compile-time`.
341 A text file containing your game defined using the Inform language.
344 A routine which is not part of an object. Unlike an `embedded
345 routine`, it must provide a name of its own, and it returns ``true``
346 when execution reaches the terminating marker ``]``.
349 A single instruction to be executed at `run-time`. See also
353 A group of `statement`\s bundled up together between braces
354 ``{...}``, which are then treated as a single unit -- as if they
355 were only one statement. They commonly appear in loops and
359 A binary file which is the output of the `compiler` and can be
360 played through the use of an `interpreter` (also known as Z-code
361 file or game file). The format of story files is standard and
362 platform-independent.
365 An option which causes the `compiler` to include extra code into the
366 story file, thus making it easier to detect certain design mistakes
367 while a game is being played.
370 A piece of text between double quotes "...", to be displayed for the
371 player's benefit at `run-time`.
374 1. an optional keyword or symbol to operate special features of the
376 2. a statement which decides among different paths of execution
377 according to the value of an expression.
380 A computer file containing words and phrases which a human can
384 A logical state which is the opposite of `false`, represented by any
385 value other than zero (typically 1).
388 A named value which can change during `run-time`. It must be
389 declared before use, either as a ``Global`` variable (available to
390 any routine within the game), or as a local variable (part of one
391 specific routine and usable by that routine alone). Variables have
392 a name and a value; it's the value which is capable of change, not
393 the name. Object `properties` behave as variables.
399 A virtual machine (an imaginary computer simulated by the
400 `interpreter`) on which story files run. Z stands for "Zork", the
401 first ever Infocom title.