7 | *C was a captain, all covered with lace;*
8 | *D was a drunkard, and had a red face.*
10 .. image:: /images/picC.png
13 onventional -- static -- fiction can be written using nothing more than
14 pencil and paper, or typewriter, or word-processor; however, the
15 requirements for producing IF are a little more extensive, and the creative
16 process slightly more complex.
18 * For static fiction, you first write the text, and then you check it by
19 reading what you've written.
21 * For IF, you still have to write all of the text, but you also have to
22 establish what text gets displayed when. Once you have written the
23 necessary Inform instructions, you use a **compiler** program to convert
24 them into a playable format. The resulting information is played by an
25 **interpreter** program, which permits you to interact with your
28 With static fiction What You Write Is What You Read, but with IF the format
29 in which you initially write the game doesn't bear much resemblance to the
30 text which the interpreter ultimately displays. For example, the "William
31 Tell" game, in the form that we wrote it, starts like this:
33 .. code-block:: inform6
35 !============================================================================
36 Constant Story "William Tell";
38 "^A simple Inform example
39 ^by Roger Firth and Sonja Kesserich.^";
44 !============================================================================
52 You will never need to look at it in the form produced by the compiler::
54 050000012C6C2C2D1EF6010A0C4416900010303230313031004253FEA90C0000
55 0000000000000000000000000000168F000000000000010200000000362E3231
58 but, as you'll notice from the full transcript in "William Tell" story on
59 page 219, the player will see the following::
61 The place: Altdorf, in the Swiss canton of Uri. The year is 1307, at
62 which time Switzerland is under rule by the Emperor Albert of
63 Habsburg. His local governor -- the vogt -- is the bullying Hermann
64 Gessler, who has placed his hat atop a wooden pole in the centre of
65 the town square; everybody who passes through the square must bow to
66 this hated symbol of imperial might...
68 Clearly, there's more to writing IF than just laying down the words in the
69 right order. Fortunately, we can make one immediate simplification: the
70 translated form produced by the Inform compiler -- those cryptic numbers
71 and letters held in what's known as the **story file** -- is designed to be
72 read by the interpreter program. The story file is an example of a
73 "binary" file, containing data intended for use only by a computer program.
74 Forget all that unreadable gibberish.
76 So that leaves just the first form -- the one starting "``Constant Story``"
77 -- which represents the tale written as a piece of IF. That's the **source
78 file** (so called because it contains the game in its original, source,
79 form) which you create on your computer. The source file is a "text" (or
80 "ASCII") file containing words and phrases which can be read -- admittedly
81 after a little tuition, which is what this guide is all about -- by humans.
83 How do you create that source file? Using a third software program: an
84 **editor**. However, unlike the compiler and interpreter, this program
85 isn't dedicated to the Inform system -- or even to IF. An editor is an
86 entirely general tool for creating and modifying text files; you've
87 probably already got a basic one on your computer (an IBM PC running
88 Windows comes with NotePad, while an Apple Macintosh has SimpleText or
89 TextEdit), or you can download a better one from the Internet. An editor
90 is like a word-processing program such as MS Word, only much less complex;
91 no fancy formatting features, no bold or italics or font control, no
92 embedded graphics; it simply enables you to type lines of text, which is
93 exactly what's needed to create an IF game.
95 If you look at the game source on the previous page, or in the "William
96 Tell" story on page 219, you'll notice ``Include "Parser";`` and ``Include
97 "VerbLib";`` a few lines down from the top of the file. These are
98 instructions to the Inform compiler to "include" -- that is, to merge in
99 the contents -- of files called ``Parser.h`` and ``VerbLib.h``. These are
100 not files which you have to create; they're standard **library files**,
101 part of the Inform system. All that you have to do is remember to Include
102 them in every game that you write. Until you've a fair understanding of
103 how Inform works, you've no need to worry about what they contain (though
104 you can look if you want to: they're readable text files, just like the
105 ones this guide will teach you to write).
107 So, we've now introduced all of the bits and pieces which you need in order to
108 write an Inform adventure game:
110 * a text **editor** program which can create and modify the **source file**
111 containing the descriptions and definitions of your game. Although it's
112 not recommended, you can even use a word-processing program to do this,
113 but you have to remember to save your game in Text File format;
115 * some Inform **library files** which you Include in your own game source
116 file in order to provide the model world -- a basic game environment and
117 lots of useful standard definitions;
119 * the Inform **compiler** program, which reads your source file (and the
120 library files) and translates your descriptions and definitions into
121 another format -- the **story file** -- intended only for...
123 * an Inform **interpreter** program, which is what players of your game
124 use. A player doesn't require the source file, library files or compiler
125 program, just the interpreter and the game in compiled format (which,
126 because it's a binary file not meaningful to human eyes, neatly
127 discourages players from cheating).
129 All of those, apart from the editor, can be downloaded for free from the IF
130 Archive. One approach is to fetch them individually, following the
131 guidance on Graham's page: visit http://www.inform-fiction.org/ and look
132 for the "Software" section. However, if you're using a PC or a Mac, you'll
133 find it easier to download a complete package containing everything that
134 you need to get started.
136 Inform on an IBM PC (running Microsoft Windows)
137 ===============================================
139 Although the Windows operating system is upgraded on a fairly regular
140 basis, its basic capabilities and ways of working have remained
141 more-or-less consistent for many years. The information here applies to
142 PCs running Windows 95 onwards.
144 .. rubric:: Installing and testing Inform
148 1. Download http://www.firthworks.com/roger/downloads/inform_pc_env.zip to
149 a temporary location on your PC.
151 2. Use a tool like WinZip to unzip the downloaded file, giving you a new
152 ``Inform`` folder. Move this folder (and its contents) to a suitable
153 location on your PC -- a good place would be ``C:\My Documents\Inform``,
154 but you could also use ``C:\Documents and Settings\yourname\My
155 Documents\Inform``, ``C:\Inform`` or ``C:\Program Files\Inform``. You
156 should now have this set of folders:
158 .. image:: /images/inform_pc_env.*
161 In order to make the download small and fast, these folders include just
162 enough to get you started as an Inform designer -- the compiler and
163 interpreter programs, the library files, the ``Ruins.inf`` example file
164 from the *Inform Designer's Manual*, and a template for your own first
165 game. A few other folders are included as placeholders where you could
166 later download additional components, if you wanted them. As soon as
167 possible, you should download the *Inform Designer's Manual* into the
168 ``Inform\Doc`` folder -- it's an essential document to have, and has
169 been omitted from this download only because of its 3MB size.
171 3. To verify that the downloaded files work properly, use Windows Explorer
172 to display the contents of the ``Inform\Games\MyGame1`` folder: you will
173 see the two files ``MyGame1.bat`` and ``MyGame1.inf``:
175 .. image:: /images/filelist1.*
178 ``MyGame1.inf`` is a tiny skeleton game in Inform source format. By
179 convention, all Inform source files have an extension of .inf; Windows
180 has an inbuilt definition for ``.inf`` files, and so shows its Type as
181 "Setup Information", but this doesn't seem to matter. If you
182 double-click the file, it should open in NotePad so that you can see how
183 it's written, though it probably won't mean much -- yet.
185 4. ``MyGame1.bat`` is an MS-DOS batch file (an old kind of text-only
186 computer program, from the days before point-and-click interfaces) which
187 runs the Inform compiler. Double-click it; a DOS window opens as the
188 game compiles, and you'll see this::
190 C:\My Documents\Inform\Games\MyGame1>..\..\Lib\Base\Inform MyGame1
191 +include_path=.\,..\..\Lib\Base,..\..\Lib\Contrib | more
193 Inform 6.30 for Win32 (27th Feb 2004)
195 C:\My Documents\Inform\Games\MyGame1>pause "at end of compilation"
196 Press any key to continue . . .
198 Press the space bar, then close the DOS window.
202 On Windows NT, 2000 and XP, the DOS window closes of its own accord
203 when you press the space bar.
205 5. A story file ``MyGame1.z5`` has appeared in the folder; this is the
206 compiled game, which you can play using an interpreter:
208 .. image:: /images/filelist2.*
211 The extension of ``.z5`` signifies that the story file contains a
212 Z-machine game in Version 5 (today's standard) format.
214 6. Use Windows Explorer to display the contents of the ``Inform\Bin\Frotz``
215 folder, and double-click ``Frotz.exe``; the interpreter presents an
216 ``Open a Z-code Game`` dialog box.
218 7. Browse to display the ``Inform\Games\MyGame1`` folder, and select
219 ``MyGame1.z5``. Click ``Open``. The game starts running in the Windows
222 8. When you tire of "playing" the game -- which won't take long -- you can
223 type the QUIT command, you can select ``File > Exit``, or you can simply
224 close the Frotz window.
226 9. Using the same techniques, you can compile and play ``Ruins.inf``, which
227 is held in the ``Inform\Games\Download`` folder. RUINS is the game used
228 as an example throughout the *Inform Designer's Manual*.
230 .. rubric:: Setting file associations
232 The business of first starting the interpreter, and then locating the story
233 file that you want to play, is clumsy and inconvenient. Fortunately, when
234 you first run the Frotz interpreter, it automatically creates an
235 association with story files whose extension is ``.z5``. From now on,
236 you'll be able to play a game simply by double-clicking its story file. If
237 some any reason this doesn't work, you can set up the association yourself:
239 1. Double-click ``MyGame1.z5``; Windows asks you to select the program
242 * type ``Z-code V5 Adventure`` as the "``Description for...``"
243 * click to select "``Always use this program...``"
246 2. Browse to display the ``Inform\Bin\Frotz`` folder, and select
247 ``Frotz.exe``. Click ``Open``.
249 .. rubric:: Changing the Windows icon
251 If the Windows icon that's displayed alongside ``MyGame1.z5`` doesn't look
252 right, you can change it.
254 1. In Windows Explorer, either select ``View > Options...`` and click
255 ``File Types``, or select ``Tools > Folder Options...`` and click ``File
258 * select the game file type in the list, which is in order either of
259 application (Frotz) or of extension (Z5)
262 2. In the ``Edit File Type`` dialog, click ``Change Icon``.
264 3. In the ``Change Icon`` dialog, ensure that the file name is
265 ``Inform\Bin\Frotz\Frotz.exe``, and select one of the displayed icons.
266 Click ``OK`` to close all the dialogs. The files in the folder should
269 .. image:: /images/filelist3.*
272 .. rubric:: Compiling using a batch file
274 You can view -- and of course change -- the contents of ``MyGame1.bat``,
275 the batch file which you double-click to run the compiler, using any text
276 editor. You'll see two lines, something like this (the first chunk is all
277 on one long line, with a space between the ``MyGame1`` and the
280 ..\..\Lib\Base\Inform MyGame1
281 +include_path=.\,..\..\Lib\Base,..\..\Lib\Contrib | more
282 pause "at end of compilation"
284 These long strings of text are command lines -- a powerful interface method
285 predating the icons and menus that most computer users know. You won't
286 need to master the command line interface in order to start using Inform,
287 but this section will tell you what these particular command lines are
288 doing. There are four parts to the first line:
290 1. ``Inform`` refers to the compiler program, and ``..\..\Lib\Base`` is the
291 name of the folder which contains it (addressed relative to *this*
292 folder, the one which holds the source file). Double-dots stand for "go
293 to the parent folder".
295 2. ``MyGame1`` is the name of the Inform source file; you don't need to
296 mention its extension of ``.inf`` if you don't want to.
298 3. ``+include_path=.\,..\..\Lib\Base,..\..\Lib\Contrib`` tells the compiler
299 where to look for files like ``Parser`` and ``VerbLib`` which you've
300 Included. Three locations are suggested: this folder, which holds the
301 source file (``.\``); the folder holding the standard library files
302 (``..\..\Lib\Base``); the folder holding useful bits and pieces
303 contributed by the Inform community (``..\..\Lib\Contrib``). The three
304 locations are searched in that order.
308 On the command line, you sometimes also see a compiler **switch**
309 such as ``-S``, used for controlling detailed aspects of how the
310 compiler operates. Rather than do that here, we find it more
311 convenient to place any necessary switches at the very top of the
312 source file, as we'll explain in the next chapter.
314 4. ``| more`` causes the compiler to pause if it finds more mistakes than
315 it can tell you about on a single screen, rather than have them scroll
316 off the top of the MS-DOS window. Press the space bar to continue the
319 The second line -- ``pause "at end of compilation"`` -- just prevents the
320 window from closing before you can read its contents, as it otherwise would
321 on Windows NT, 2000 and XP.
323 You'll need to have a new batch file like this to match each new source
324 file which you create. The only item which will differ in the new file is
325 the name of the Inform source file -- ``MyGame1`` in this example. You
326 must change this to match the name of the new source file; everything else
327 can stay the same in each ``.bat`` file that you create.
329 .. rubric:: Getting a better editor
331 Although NotePad is adequate when you're getting started, you'll find life
332 much easier if you obtain a more powerful editor program. We recommend
333 TextPad, available as shareware from http://www.textpad.com/; in addition,
334 there are some detailed instructions at
335 http://www.onyxring.com/informguide.aspx?article=14 on how to improve the
336 way that TextPad works with Inform. The biggest single improvement, the
337 one that will make game development dramatically simpler, is being able to
338 compile your source file *from within* the editor. No need to save the
339 file, switch to another window and double-click the batch file (and indeed,
340 no further need for the batch file itself): just press a key while editing
341 the file -- and it compiles there and then. You can also run the
342 interpreter with similar ease. The convenience of doing this far outweighs
343 the small amount of time needed to obtain and configure TextPad.
345 Inform on an Apple Macintosh (running OS X)
346 ===========================================
348 Whereas our instructions for using Inform on a PC apply to just about all
349 versions of Windows, on the Macintosh we need to be more precise. Our
350 guidance here is specifically for Mac OS X, rather than for its predecessor
351 OS 9, and it may be helpful if we first mention a few relevant differences.
353 Mac OS X is a robust system constructed around -- or on top of -- BSD
354 [#bsd]_ UNIX. There are several kinds of applications that will run on
357 * Aqua: specifically designed for the Graphical User Interface of Mac OS X,
358 and taking advantage of its underlying technologies. Broadly, there
359 are two types of Aqua application:
361 * Cocoa: built with programming tools designed for Mac OS X.
363 * Carbon: built with the programming tools designed for Mac OS 9 and
364 earlier versions, but "translated" to take advantage of OS X.
366 * Classic: designed to work on Mac OS 9 and earlier versions. They need to
367 run in the Classic environment of OS X; roughly speaking, Classic is an
368 emulation of the older Mac systems.
370 * X11: based on a windowing system designed for the UNIX/Linux world. They
371 need an X-Windows server to run, and their appearance and functionality
372 may seem a lot different to what the Aqua user expects.
374 * UNIX: most UNIX programs (including Linux) will run on your Mac OS X, but
375 they usually have to be accessed (or configured) from the UNIX core of
376 your Mac, through the Terminal utility.
378 These differences may be significant, since some of the tools designed to
379 develop and run IF on a Mac system (for example, ones you'll find in the
380 Archive) have been built by programmers working in different environments
381 with varying technologies. We have tried to select tools that will make
382 your life easy as a beginner, but in time you may want to investigate
383 alternative approaches.
385 .. rubric:: Installing and testing Inform
389 1. Download http://www.firthworks.com/roger/downloads/inform_macosx_env.sit
390 to a temporary location on your Mac.
392 2. Use a tool like StuffIt Expander to unpack the downloaded file (if your
393 system configuration is standard, a mere double-click will make it
394 self-extract at the current location, if it hasn't already expanded all
395 by itself). You'll now have a new ``Inform`` folder. Move this folder
396 (and its contents) to a suitable location in your Mac.
400 It is a good idea for now to place it in your home directory;
401 otherwise, a few pre-configured items may not work as explained.
402 Once you learn the basics of the configuration, you may move the
403 Inform folder to a different location and hack all the defaults like
404 the professionals do.
406 You should now have this set of folders:
408 .. image:: /images/inform_mac_env.*
411 In order to make the download small and fast, these folders include just
412 enough to get you started as an Inform designer -- the compiler and
413 interpreter programs, the library files, the ``Ruins.inf`` example from
414 the *Inform Designer's Manual*, and a template for your own first game,
415 which you may copy and rename each time you begin a new Inform project.
416 A few other folders are included as placeholders where you could later
417 download additional components, if you wanted them. As soon as
418 possible, you should download the *Inform Designer's Manual* into the
419 ``Inform/Doc`` folder -- it's an essential document to have, and has
420 been omitted from this download only because of its 3MB size.
422 3. To verify that the downloaded files work properly, use the Finder to
423 display the contents of the ``Inform/Games/MyGame1`` folder: you will see
424 the files ``MyGame1.command`` and ``MyGame1.inf``:
426 .. image:: /images/mac_filelist1.*
429 ``MyGame1.inf`` is a tiny skeleton game in Inform source format. By
430 convention, all Inform source files have an extension of ``.inf``.
431 However, Mac OS X may show its Kind as "FUJI BAS IMG document", and try
432 to open it with GraphicConverter. If you're not a regular user of FUJI
433 BAS IMG documents, you'll probably want to change this. Either:
435 * right-click on the file (or Ctrl-click)
437 * select ``Open with`` and choose ``Other...``
439 * in the ``Open with`` dialog, go to the ``Applications`` folder and
442 * click to select "``Always open with``"
448 * right-click on the file (or Ctrl-click)
450 * press Option, select ``Always open with`` and choose ``Other...``
452 * in the ``Open with`` dialog, go to the ``Applications`` folder and
457 Now, if you double-click the file, it should open in TextEdit so that
458 you can see how it's written, though it probably won't mean much -- yet.
460 The above process may affect only this specific file. To change the
461 program that opens by default all ``.inf`` files, try this:
463 * right-click on the file (or Ctrl-click)
465 * select ``Get Info``
467 * in the ``Open with`` tab, select TextEdit as the application
469 * click the ``Change All...`` button, and confirm the change when asked.
471 4. ``MyGame1.command`` is a Terminal Shell Script (a UNIX executable
472 command-line file, a kind of text-only computer program from the days
473 before point-and-click interfaces) which runs the Inform compiler.
474 Double-click it; a UNIX window opens as the game compiles, and you'll
475 see something like this (the working path will reflect your folder
478 Last login: Sat Jul 3 03:07:51 on ttyp1
480 /Users/Dave/Inform/Games/MyGame1/MyGame1.command; [Hal:~] Dave%
481 /Users/Dave/Inform/Games/MyGame1/MyGame1.command; exit
482 Inform 6.30 (27th Feb 2004)
488 Verify this output. It's what's in the PDF, but the command prompt
489 looks like it's in the wrong place.
491 5. A story file ``MyGame1.z5`` has appeared in the folder; this is the
492 compiled game, which you can play using an interpreter:
494 .. image:: /images/mac_filelist2.*
497 The extension of ``.z5`` signifies that the story file contains a
498 Z-machine game in Version 5 (today's standard) format.
500 6. Use the Finder to display the contents of the ``Inform/Bin/Zoom``
501 folder, and double-click ``Zoom``; the interpreter presents an ``Open``
504 7. Browse to display the ``Inform/Games/MyGame1`` folder, and select
505 ``MyGame1.z5``. Click ``Open``. The game starts running in the Zoom
508 8. When you tire of "playing" the game -- which won't take long -- you can
509 type the QUIT command, you can select ``Zoom > Quit Zoom``, or you can
510 simply close the Zoom window.
512 .. rubric:: Setting file associations
514 The business of first starting the interpreter, and then locating the story
515 file that you want to play, is clumsy and inconvenient. Fortunately, when
516 the system first "sees" the Zoom interpreter (which is a nice Aqua
517 application) it automatically creates an association with story files whose
518 extension is ``.z5`` (and with other Infocom formats). From now on, you'll
519 be able to play a game simply by double-clicking its story file.
521 The files in the folder should now look like this:
523 .. image:: /images/mac_filelist3.*
526 .. rubric:: Compiling using a command-line file
528 If you have followed these instructions to configure your system, every
529 time that you need to compile your source code you just have to
530 double-click on the file ``MyGame1.command``. However, this file is good
531 only for this folder and for ``MyGame1.inf``.
533 If you want to start coding another game, you may copy the folder
534 ``MyGame1`` with all its contents and rename it as you please (for example,
535 ``MyGame2`` or something more appropriate). Inside the folder, you'll also
536 want to rename the relevant files:
538 ``MyGame1.inf`` might become ``MyGame2.inf``, or ``MobyDick.inf``,
541 ``MyGame1.command`` would change to match: ``MyGame2.command``, or
542 ``MobyDick.command``.
544 You can view -- and of course change -- the contents of
545 ``MyGame2.command``, the command file which you double-click to run the
546 compiler, using any text editor. You'll see two lines, something like this
547 (the second chunk is all on one long line, with a space between the
548 ``MyGame1`` and the ``+include_path``)::
550 cd ~/Inform/Games/MyGame1/
551 ../../Lib/Base/inform630_macosx MyGame1
552 +include_path=./,../../Lib/Base,../../Lib/Contrib
554 These long strings of text are command lines -- a powerful interface method
555 predating the icons and menus that most computer users know. You won't
556 need to master the command line interface in order to start using Inform,
557 but this section will introduce you to a few basic concepts to get your
558 bearings. The first line changes the working directory to
559 ``~/Inform/Games/MyGame1/``. The command ``cd`` (also known as ``chdir``,
560 short for "Change Directory to") lets you travel to the desired folder,
561 specified by the path, in this case: ``~/Inform/Games/MyGame1/``. The
562 ``~`` symbol stands for your home directory. That is, if your user name
563 were Dave, the above path is equal to::
565 /Users/Dave/Inform/Games/MyGame1/
567 You want to change that line so that it reads: ``cd
568 ~/Inform/Games/MyGame2/``
570 There are three parts to the second line:
572 1. ``inform630_macosx`` refers to the compiler program, and
573 ``../../Lib/Base`` is the name of the folder which contains it
574 (addressed relative to *this* folder, the one which holds the source
575 file). Double-dots stand for "go to the parent folder".
577 2. ``MyGame1`` is the name of the Inform source file; you don't need to
578 mention its extension of ``.inf`` if you don't want to. You'll want to
579 change this to match the name of your new file: ``MyGame2``.
581 3. ``+include_path=./,../../Lib/Base,../../Lib/Contrib`` tells the compiler
582 where to look for files like ``Parser`` and ``VerbLib`` which you've
583 Included in the source file (this may sound confusing now, but it will
584 make a lot of sense after you've delved a bit deeper into this Guide).
585 Three locations are suggested, separated by commas: this folder, which
586 holds the source file (``./``); the folder holding the standard library
587 files (``../../Lib/Base``); the folder holding useful bits and pieces
588 contributed by the Inform community (``../../Lib/Contrib``). The three
589 locations are searched in that order.
593 On the command line, you sometimes also see a compiler switch such as
594 ``-S``, used for controlling detailed aspects of how the compiler
595 operates. Rather than do that here, we find it more convenient to
596 place any necessary switches at the very top of the source file, as
597 we'll explain in the next chapter.
599 Once you've finished editing those lines, ``Save`` the file (not
600 ``SaveAs``), overwriting the original, and make sure that your text editor
601 doesn't append an extension like ``.txt`` (TextEdit, the default editor
602 that comes with OS X, is polite enough to ask you about this).
604 You'll need to have a new command file like this to match each new source
605 file which you create. The only item which will differ in the new file is
606 the name of the Inform source file -- ``MyGameN``. You must change this to
607 match the name of the new source file; everything else can stay the same in
608 each ``.command`` file that you create.
610 .. rubric:: Making your own command-line file
612 There are two peculiarities by which your system understands that
613 ``MyGame1.command`` is a Terminal Shell Script. One is the extension
614 ``.command``, and the other is an attribute of the file which marks it as
615 "executable" (the "executable bits"). If it doesn't meet both conditions,
616 ``MyGame1.command`` won't run as it should. You have to be careful when
617 editing this file: if you were, for instance, to open it in a text editor
618 and save it to a different location with a different name, the executable
619 bits might get lost, and when you double-click it, you would see:
621 .. image:: /images/mac_exec_error.*
624 To make a command file from scratch (also, to fix this problem) you can
627 1. Open any text editor and write (using your own path)::
629 cd ~/Inform/Games/MyGameN/
630 ../../Lib/Base/inform630_macosx MyGameN
631 +include_path=./,../../Lib/Base,../../Lib/Contrib
633 where ``MyGameN`` stands for the name you have chosen for your Inform
636 2. Save the file in the folder ``MyGameN`` and call it ``MyGameN.command``.
637 Make sure that the text editor doesn't append a ``.txt`` extension; if
638 it does, rename the file manually.
640 3. Go to ``Applications > Utilities`` and double-click on ``Terminal``.
641 This opens the utility which provides you with a set of windows to
642 access the UNIX command line. Supposing the computer is named Hal, and
643 the user Dave, you should see something like this::
645 Last login: Wed Jun 30 18:05:55 on ttyp1
649 4. Every time that you open a Terminal window, you're at your home
650 directory (as noted by the tilde after the computer's name). You can
651 travel to your working folder by typing::
653 cd Inform/Games/MyGameN
655 You'll see how the path changes::
657 [Hal:~/Inform/Games/MyGameN] Dave%
659 Now you can make the command file executable with::
661 chmod 777 MyGameN.command
663 5. Alternatively, you can omit the cd command if you give the full path to
666 chmod 777 ~/Inform/Games/MyGameN/MyGameN.command
668 This sets the executable bits for the file ``MyGameN.command``.
670 6. Close the Terminal window.
672 Now, every time you need to compile your game, you can just double-click on
673 ``MyGameN.command`` from the Finder.
675 .. rubric:: Getting a better editor
677 Although TextEdit is adequate when you're getting started, you'll find life
678 much easier if you obtain a more powerful editor program. We'd really like
679 to recommend one -- there's an exciting list of possibilities at
680 http://osx.hyperjeff.net/Apps/apps.php?sub=5 -- but at the time of writing
681 none of them seems outstandingly suited to IF authorship. If you find one
682 that works really well, please let us know.
684 .. rubric:: More about the editor
686 As well as the ones that we recommend, other good text editors are listed
687 at http://www.firthworks.com/roger/editors/. One feature that's well worth
688 looking out for is "hotkey compilation" -- being able to run the compiler
689 from *within* the editor. Another is "syntax colouring", where the editor
690 understands enough of Inform's syntax rules to colour-code your source
691 file; for example: red for brackets, braces and parentheses ``[ ]`` ``{ }``
692 and ``( )``, blue for reserved words like ``Object`` and ``print``, green
693 for items in quotes like '...' and "...", and so on. Syntax colouring is
694 of great assistance in getting your source file correct and thus avoiding
695 silly compilation errors.
697 .. rubric:: More about the compiler
699 The Inform compiler is a powerful but undramatic software tool; it does an
700 awful lot of work, but it does it all at once, without stopping to ask you
701 any questions. Its input is a readable text source file; the output is a
702 story file, also sometimes known as a **Z-code file** (because it contains
703 the game translated into code for the Z-machine, which we describe in the
706 If you're lucky, the compiler will translate your source file into Z-code;
707 perhaps surprisingly, it doesn't display any form of "success" message when
708 it succeeds. Often, however, it fails, because of mistakes which you've
709 made when writing the game. Inform defines a set of rules -- a capital
710 letter here, a comma there, these words only in a certain order, those
711 words spelled just so -- about which the compiler is extremely fussy. If
712 you accidentally break the rules, the compiler complains: it refuses to
713 write a Z-code file. *Do not worry about this*: the rules are easy to
714 learn, but just as easy to break, and all Inform designers inadvertently do
715 so on a regular basis. There's some additional information about dealing
716 with these mistakes, and about controlling how the compiler behaves, in
717 "Compiling your game" on page 189.
719 .. rubric:: More about the interpreter
721 One of the big advantages of the way Inform works is that a compiled game
722 -- the Z-code story file -- is portable between different computers.
723 That's not just from one PC to another: exactly the same story file will
724 run on a PC, a Mac, an Amiga, UNIX workstations, IBM mainframes, PalmOS
725 hand-helds, and on dozens of other past, present and future computers. The
726 magic that makes this happen is the interpreter program, a software tool
727 which pretends to be a simple computer called a **Z-machine**. The
728 Z-machine is an imaginary (or "virtual") computer, but its design has been
729 very carefully specified, so that an expert programmer can quite easily
730 build one. And that's exactly what has happened: a Macintosh guru has
731 built an Inform interpreter which runs on Apple Macs, a UNIX wizard has
732 built one for UNIX workstations, and so on. Sometimes, you even get a
733 choice; for popular machines like the PC and the Mac there are several
734 interpreters available. And the wonderful thing is: each of those
735 interpreters, on each of those computers, is able to play every Inform game
736 that's ever been written *and*, as a surprise bonus, all of the classic
737 1980s Infocom games like "Zork" and "The Hitchhiker's Guide to the Galaxy"
740 (Actually, that last sentence is a slight exaggeration; a few games are
741 very large, or have pictures included within them, and not all interpreters
742 can handle this. However, with that small pinch of salt, it's pretty
745 That's enough waffling: let's get started! It's time to begin designing
748 .. rubric:: Footnotes
751 "BSD" stands for Berkeley Software Distribution, the name of the UNIX
752 derivative distributed in the 1970s from the University of California,
753 Berkeley, and used collectively for the modern descendants of those