7 | *C was a captain, all covered with lace;*
8 | *D was a drunkard, and had a red face.*
10 Conventional -- static -- fiction can be written using nothing more than
11 pencil and paper, or typewriter, or word-processor; however, the
12 requirements for producing IF are a little more extensive, and the creative
13 process slightly more complex.
15 * For static fiction, you first write the text, and then you check it by
16 reading what you've written.
18 * For IF, you still have to write all of the text, but you also have to
19 establish what text gets displayed when. Once you have written the
20 necessary Inform instructions, you use a **compiler** program to convert
21 them into a playable format. The resulting information is played by an
22 **interpreter** program, which permits you to interact with your
25 With static fiction What You Write Is What You Read, but with IF the format
26 in which you initially write the game doesn't bear much resemblance to the
27 text which the interpreter ultimately displays. For example, the "William
28 Tell" game, in the form that we wrote it, starts like this:
30 .. code-block:: inform6
32 !============================================================================
33 Constant Story "William Tell";
35 "^A simple Inform example
36 ^by Roger Firth and Sonja Kesserich.^";
41 !============================================================================
49 You will never need to look at it in the form produced by the compiler::
51 050000012C6C2C2D1EF6010A0C4416900010303230313031004253FEA90C0000
52 0000000000000000000000000000168F000000000000010200000000362E3231
55 but, as you'll notice from the full transcript in "William Tell" story on
56 page 219, the player will see the following::
58 The place: Altdorf, in the Swiss canton of Uri. The year is 1307, at
59 which time Switzerland is under rule by the Emperor Albert of
60 Habsburg. His local governor -- the vogt -- is the bullying Hermann
61 Gessler, who has placed his hat atop a wooden pole in the centre of
62 the town square; everybody who passes through the square must bow to
63 this hated symbol of imperial might...
65 Clearly, there's more to writing IF than just laying down the words in the
66 right order. Fortunately, we can make one immediate simplification: the
67 translated form produced by the Inform compiler -- those cryptic numbers
68 and letters held in what's known as the **story file** -- is designed to be
69 read by the interpreter program. The story file is an example of a
70 "binary" file, containing data intended for use only by a computer program.
71 Forget all that unreadable gibberish.
73 So that leaves just the first form -- the one starting "``Constant Story``"
74 -- which represents the tale written as a piece of IF. That's the **source
75 file** (so called because it contains the game in its original, source,
76 form) which you create on your computer. The source file is a "text" (or
77 "ASCII") file containing words and phrases which can be read -- admittedly
78 after a little tuition, which is what this guide is all about -- by humans.
80 How do you create that source file? Using a third software program: an
81 **editor**. However, unlike the compiler and interpreter, this program
82 isn't dedicated to the Inform system -- or even to IF. An editor is an
83 entirely general tool for creating and modifying text files; you've
84 probably already got a basic one on your computer (an IBM PC running
85 Windows comes with NotePad, while an Apple Macintosh has SimpleText or
86 TextEdit), or you can download a better one from the Internet. An editor
87 is like a word-processing program such as MS Word, only much less complex;
88 no fancy formatting features, no bold or italics or font control, no
89 embedded graphics; it simply enables you to type lines of text, which is
90 exactly what's needed to create an IF game.
92 If you look at the game source on the previous page, or in the "William
93 Tell" story on page 219, you'll notice ``Include "Parser";`` and ``Include
94 "VerbLib";`` a few lines down from the top of the file. These are
95 instructions to the Inform compiler to "include" -- that is, to merge in
96 the contents -- of files called ``Parser.h`` and ``VerbLib.h``. These are
97 not files which you have to create; they're standard **library files**,
98 part of the Inform system. All that you have to do is remember to Include
99 them in every game that you write. Until you've a fair understanding of
100 how Inform works, you've no need to worry about what they contain (though
101 you can look if you want to: they're readable text files, just like the
102 ones this guide will teach you to write).
104 So, we've now introduced all of the bits and pieces which you need in order to
105 write an Inform adventure game:
107 * a text **editor** program which can create and modify the **source file**
108 containing the descriptions and definitions of your game. Although it's
109 not recommended, you can even use a word-processing program to do this,
110 but you have to remember to save your game in Text File format;
112 * some Inform **library files** which you Include in your own game source
113 file in order to provide the model world -- a basic game environment and
114 lots of useful standard definitions;
116 * the Inform **compiler** program, which reads your source file (and the
117 library files) and translates your descriptions and definitions into
118 another format -- the **story file** -- intended only for...
120 * an Inform **interpreter** program, which is what players of your game
121 use. A player doesn't require the source file, library files or compiler
122 program, just the interpreter and the game in compiled format (which,
123 because it's a binary file not meaningful to human eyes, neatly
124 discourages players from cheating).
126 All of those, apart from the editor, can be downloaded for free from the IF
127 Archive. One approach is to fetch them individually, following the
128 guidance on Graham's page: visit http://www.inform-fiction.org/ and look
129 for the "Software" section. However, if you're using a PC or a Mac, you'll
130 find it easier to download a complete package containing everything that
131 you need to get started.
133 Inform on an IBM PC (running Microsoft Windows)
134 ===============================================
136 Although the Windows operating system is upgraded on a fairly regular
137 basis, its basic capabilities and ways of working have remained
138 more-or-less consistent for many years. The information here applies to
139 PCs running Windows 95 onwards.
141 .. rubric:: Installing and testing Inform
145 1. Download http://www.firthworks.com/roger/downloads/inform_pc_env.zip to
146 a temporary location on your PC.
148 2. Use a tool like WinZip to unzip the downloaded file, giving you a new
149 ``Inform`` folder. Move this folder (and its contents) to a suitable
150 location on your PC -- a good place would be ``C:\My Documents\Inform``,
151 but you could also use ``C:\Documents and Settings\yourname\My
152 Documents\Inform``, ``C:\Inform`` or ``C:\Program Files\Inform``. You
153 should now have this set of folders:
155 .. image:: /images/inform_pc_env.*
158 In order to make the download small and fast, these folders include just
159 enough to get you started as an Inform designer -- the compiler and
160 interpreter programs, the library files, the ``Ruins.inf`` example file
161 from the *Inform Designer's Manual*, and a template for your own first
162 game. A few other folders are included as placeholders where you could
163 later download additional components, if you wanted them. As soon as
164 possible, you should download the *Inform Designer's Manual* into the
165 ``Inform\Doc`` folder -- it's an essential document to have, and has
166 been omitted from this download only because of its 3MB size.
168 3. To verify that the downloaded files work properly, use Windows Explorer
169 to display the contents of the ``Inform\Games\MyGame1`` folder: you will
170 see the two files ``MyGame1.bat`` and ``MyGame1.inf``:
172 .. image:: /images/filelist1.*
175 ``MyGame1.inf`` is a tiny skeleton game in Inform source format. By
176 convention, all Inform source files have an extension of .inf; Windows
177 has an inbuilt definition for ``.inf`` files, and so shows its Type as
178 "Setup Information", but this doesn't seem to matter. If you
179 double-click the file, it should open in NotePad so that you can see how
180 it's written, though it probably won't mean much -- yet.
182 4. ``MyGame1.bat`` is an MS-DOS batch file (an old kind of text-only
183 computer program, from the days before point-and-click interfaces) which
184 runs the Inform compiler. Double-click it; a DOS window opens as the
185 game compiles, and you'll see this::
187 C:\My Documents\Inform\Games\MyGame1>..\..\Lib\Base\Inform MyGame1
188 +include_path=.\,..\..\Lib\Base,..\..\Lib\Contrib | more
190 Inform 6.30 for Win32 (27th Feb 2004)
192 C:\My Documents\Inform\Games\MyGame1>pause "at end of compilation"
193 Press any key to continue . . .
195 Press the space bar, then close the DOS window.
199 On Windows NT, 2000 and XP, the DOS window closes of its own accord
200 when you press the space bar.
202 5. A story file ``MyGame1.z5`` has appeared in the folder; this is the
203 compiled game, which you can play using an interpreter:
205 .. image:: /images/filelist2.*
208 The extension of ``.z5`` signifies that the story file contains a
209 Z-machine game in Version 5 (today's standard) format.
211 6. Use Windows Explorer to display the contents of the ``Inform\Bin\Frotz``
212 folder, and double-click ``Frotz.exe``; the interpreter presents an
213 ``Open a Z-code Game`` dialog box.
215 7. Browse to display the ``Inform\Games\MyGame1`` folder, and select
216 ``MyGame1.z5``. Click ``Open``. The game starts running in the Windows
219 8. When you tire of "playing" the game -- which won't take long -- you can
220 type the QUIT command, you can select ``File > Exit``, or you can simply
221 close the Frotz window.
223 9. Using the same techniques, you can compile and play ``Ruins.inf``, which
224 is held in the ``Inform\Games\Download`` folder. RUINS is the game used
225 as an example throughout the *Inform Designer's Manual*.
227 .. rubric:: Setting file associations
229 The business of first starting the interpreter, and then locating the story
230 file that you want to play, is clumsy and inconvenient. Fortunately, when
231 you first run the Frotz interpreter, it automatically creates an
232 association with story files whose extension is ``.z5``. From now on,
233 you'll be able to play a game simply by double-clicking its story file. If
234 some any reason this doesn't work, you can set up the association yourself:
236 1. Double-click ``MyGame1.z5``; Windows asks you to select the program
239 * type ``Z-code V5 Adventure`` as the "``Description for...``"
240 * click to select "``Always use this program...``"
243 2. Browse to display the ``Inform\Bin\Frotz`` folder, and select
244 ``Frotz.exe``. Click ``Open``.
246 .. rubric:: Changing the Windows icon
248 If the Windows icon that's displayed alongside ``MyGame1.z5`` doesn't look
249 right, you can change it.
251 1. In Windows Explorer, either select ``View > Options...`` and click
252 ``File Types``, or select ``Tools > Folder Options...`` and click ``File
255 * select the game file type in the list, which is in order either of
256 application (Frotz) or of extension (Z5)
259 2. In the ``Edit File Type`` dialog, click ``Change Icon``.
261 3. In the ``Change Icon`` dialog, ensure that the file name is
262 ``Inform\Bin\Frotz\Frotz.exe``, and select one of the displayed icons.
263 Click ``OK`` to close all the dialogs. The files in the folder should
266 .. image:: /images/filelist3.*
269 .. rubric:: Compiling using a batch file
271 You can view -- and of course change -- the contents of ``MyGame1.bat``,
272 the batch file which you double-click to run the compiler, using any text
273 editor. You'll see two lines, something like this (the first chunk is all
274 on one long line, with a space between the ``MyGame1`` and the
277 ..\..\Lib\Base\Inform MyGame1
278 +include_path=.\,..\..\Lib\Base,..\..\Lib\Contrib | more
279 pause "at end of compilation"
281 These long strings of text are command lines -- a powerful interface method
282 predating the icons and menus that most computer users know. You won't
283 need to master the command line interface in order to start using Inform,
284 but this section will tell you what these particular command lines are
285 doing. There are four parts to the first line:
287 1. ``Inform`` refers to the compiler program, and ``..\..\Lib\Base`` is the
288 name of the folder which contains it (addressed relative to *this*
289 folder, the one which holds the source file). Double-dots stand for "go
290 to the parent folder".
292 2. ``MyGame1`` is the name of the Inform source file; you don't need to
293 mention its extension of ``.inf`` if you don't want to.
295 3. ``+include_path=.\,..\..\Lib\Base,..\..\Lib\Contrib`` tells the compiler
296 where to look for files like ``Parser`` and ``VerbLib`` which you've
297 Included. Three locations are suggested: this folder, which holds the
298 source file (``.\``); the folder holding the standard library files
299 (``..\..\Lib\Base``); the folder holding useful bits and pieces
300 contributed by the Inform community (``..\..\Lib\Contrib``). The three
301 locations are searched in that order.
305 On the command line, you sometimes also see a compiler **switch**
306 such as ``-S``, used for controlling detailed aspects of how the
307 compiler operates. Rather than do that here, we find it more
308 convenient to place any necessary switches at the very top of the
309 source file, as we'll explain in the next chapter.
311 4. ``| more`` causes the compiler to pause if it finds more mistakes than
312 it can tell you about on a single screen, rather than have them scroll
313 off the top of the MS-DOS window. Press the space bar to continue the
316 The second line -- ``pause "at end of compilation"`` -- just prevents the
317 window from closing before you can read its contents, as it otherwise would
318 on Windows NT, 2000 and XP.
320 You'll need to have a new batch file like this to match each new source
321 file which you create. The only item which will differ in the new file is
322 the name of the Inform source file -- ``MyGame1`` in this example. You
323 must change this to match the name of the new source file; everything else
324 can stay the same in each ``.bat`` file that you create.
326 .. rubric:: Getting a better editor
328 Although NotePad is adequate when you're getting started, you'll find life
329 much easier if you obtain a more powerful editor program. We recommend
330 TextPad, available as shareware from http://www.textpad.com/; in addition,
331 there are some detailed instructions at
332 http://www.onyxring.com/informguide.aspx?article=14 on how to improve the
333 way that TextPad works with Inform. The biggest single improvement, the
334 one that will make game development dramatically simpler, is being able to
335 compile your source file *from within* the editor. No need to save the
336 file, switch to another window and double-click the batch file (and indeed,
337 no further need for the batch file itself): just press a key while editing
338 the file -- and it compiles there and then. You can also run the
339 interpreter with similar ease. The convenience of doing this far outweighs
340 the small amount of time needed to obtain and configure TextPad.
342 Inform on an Apple Macintosh (running OS X)
343 ===========================================
345 Whereas our instructions for using Inform on a PC apply to just about all
346 versions of Windows, on the Macintosh we need to be more precise. Our
347 guidance here is specifically for Mac OS X, rather than for its predecessor
348 OS 9, and it may be helpful if we first mention a few relevant differences.
350 Mac OS X is a robust system constructed around -- or on top of -- BSD
351 [#bsd]_ UNIX. There are several kinds of applications that will run on
354 * Aqua: specifically designed for the Graphical User Interface of Mac OS X,
355 and taking advantage of its underlying technologies. Broadly, there
356 are two types of Aqua application:
358 * Cocoa: built with programming tools designed for Mac OS X.
360 * Carbon: built with the programming tools designed for Mac OS 9 and
361 earlier versions, but "translated" to take advantage of OS X.
363 * Classic: designed to work on Mac OS 9 and earlier versions. They need to
364 run in the Classic environment of OS X; roughly speaking, Classic is an
365 emulation of the older Mac systems.
367 * X11: based on a windowing system designed for the UNIX/Linux world. They
368 need an X-Windows server to run, and their appearance and functionality
369 may seem a lot different to what the Aqua user expects.
371 * UNIX: most UNIX programs (including Linux) will run on your Mac OS X, but
372 they usually have to be accessed (or configured) from the UNIX core of
373 your Mac, through the Terminal utility.
375 These differences may be significant, since some of the tools designed to
376 develop and run IF on a Mac system (for example, ones you'll find in the
377 Archive) have been built by programmers working in different environments
378 with varying technologies. We have tried to select tools that will make
379 your life easy as a beginner, but in time you may want to investigate
380 alternative approaches.
382 .. rubric:: Installing and testing Inform
386 1. Download http://www.firthworks.com/roger/downloads/inform_macosx_env.sit
387 to a temporary location on your Mac.
389 2. Use a tool like StuffIt Expander to unpack the downloaded file (if your
390 system configuration is standard, a mere double-click will make it
391 self-extract at the current location, if it hasn't already expanded all
392 by itself). You'll now have a new ``Inform`` folder. Move this folder
393 (and its contents) to a suitable location in your Mac.
397 It is a good idea for now to place it in your home directory;
398 otherwise, a few pre-configured items may not work as explained.
399 Once you learn the basics of the configuration, you may move the
400 Inform folder to a different location and hack all the defaults like
401 the professionals do.
403 You should now have this set of folders:
405 .. image:: /images/inform_mac_env.*
408 In order to make the download small and fast, these folders include just
409 enough to get you started as an Inform designer -- the compiler and
410 interpreter programs, the library files, the ``Ruins.inf`` example from
411 the *Inform Designer's Manual*, and a template for your own first game,
412 which you may copy and rename each time you begin a new Inform project.
413 A few other folders are included as placeholders where you could later
414 download additional components, if you wanted them. As soon as
415 possible, you should download the *Inform Designer's Manual* into the
416 ``Inform/Doc`` folder -- it's an essential document to have, and has
417 been omitted from this download only because of its 3MB size.
419 3. To verify that the downloaded files work properly, use the Finder to
420 display the contents of the ``Inform/Games/MyGame1`` folder: you will see
421 the files ``MyGame1.command`` and ``MyGame1.inf``:
423 .. image:: /images/mac_filelist1.*
426 ``MyGame1.inf`` is a tiny skeleton game in Inform source format. By
427 convention, all Inform source files have an extension of ``.inf``.
428 However, Mac OS X may show its Kind as "FUJI BAS IMG document", and try
429 to open it with GraphicConverter. If you're not a regular user of FUJI
430 BAS IMG documents, you'll probably want to change this. Either:
432 * right-click on the file (or Ctrl-click)
434 * select ``Open with`` and choose ``Other...``
436 * in the ``Open with`` dialog, go to the ``Applications`` folder and
439 * click to select "``Always open with``"
445 * right-click on the file (or Ctrl-click)
447 * press Option, select ``Always open with`` and choose ``Other...``
449 * in the ``Open with`` dialog, go to the ``Applications`` folder and
454 Now, if you double-click the file, it should open in TextEdit so that
455 you can see how it's written, though it probably won't mean much -- yet.
457 The above process may affect only this specific file. To change the
458 program that opens by default all ``.inf`` files, try this:
460 * right-click on the file (or Ctrl-click)
462 * select ``Get Info``
464 * in the ``Open with`` tab, select TextEdit as the application
466 * click the ``Change All...`` button, and confirm the change when asked.
468 4. ``MyGame1.command`` is a Terminal Shell Script (a UNIX executable
469 command-line file, a kind of text-only computer program from the days
470 before point-and-click interfaces) which runs the Inform compiler.
471 Double-click it; a UNIX window opens as the game compiles, and you'll
472 see something like this (the working path will reflect your folder
475 Last login: Sat Jul 3 03:07:51 on ttyp1
477 /Users/Dave/Inform/Games/MyGame1/MyGame1.command; [Hal:~] Dave%
478 /Users/Dave/Inform/Games/MyGame1/MyGame1.command; exit
479 Inform 6.30 (27th Feb 2004)
485 Verify this output. It's what's in the PDF, but the command prompt
486 looks like it's in the wrong place.
488 5. A story file ``MyGame1.z5`` has appeared in the folder; this is the
489 compiled game, which you can play using an interpreter:
491 .. image:: /images/mac_filelist2.*
494 The extension of ``.z5`` signifies that the story file contains a
495 Z-machine game in Version 5 (today's standard) format.
497 6. Use the Finder to display the contents of the ``Inform/Bin/Zoom``
498 folder, and double-click ``Zoom``; the interpreter presents an ``Open``
501 7. Browse to display the ``Inform/Games/MyGame1`` folder, and select
502 ``MyGame1.z5``. Click ``Open``. The game starts running in the Zoom
505 8. When you tire of "playing" the game -- which won't take long -- you can
506 type the QUIT command, you can select ``Zoom > Quit Zoom``, or you can
507 simply close the Zoom window.
509 .. rubric:: Setting file associations
511 The business of first starting the interpreter, and then locating the story
512 file that you want to play, is clumsy and inconvenient. Fortunately, when
513 the system first "sees" the Zoom interpreter (which is a nice Aqua
514 application) it automatically creates an association with story files whose
515 extension is ``.z5`` (and with other Infocom formats). From now on, you'll
516 be able to play a game simply by double-clicking its story file.
518 The files in the folder should now look like this:
520 .. image:: /images/mac_filelist3.*
523 .. rubric:: Compiling using a command-line file
525 If you have followed these instructions to configure your system, every
526 time that you need to compile your source code you just have to
527 double-click on the file ``MyGame1.command``. However, this file is good
528 only for this folder and for ``MyGame1.inf``.
530 If you want to start coding another game, you may copy the folder
531 ``MyGame1`` with all its contents and rename it as you please (for example,
532 ``MyGame2`` or something more appropriate). Inside the folder, you'll also
533 want to rename the relevant files:
535 ``MyGame1.inf`` might become ``MyGame2.inf``, or ``MobyDick.inf``,
538 ``MyGame1.command`` would change to match: ``MyGame2.command``, or
539 ``MobyDick.command``.
541 You can view -- and of course change -- the contents of
542 ``MyGame2.command``, the command file which you double-click to run the
543 compiler, using any text editor. You'll see two lines, something like this
544 (the second chunk is all on one long line, with a space between the
545 ``MyGame1`` and the ``+include_path``)::
547 cd ~/Inform/Games/MyGame1/
548 ../../Lib/Base/inform630_macosx MyGame1
549 +include_path=./,../../Lib/Base,../../Lib/Contrib
551 These long strings of text are command lines -- a powerful interface method
552 predating the icons and menus that most computer users know. You won't
553 need to master the command line interface in order to start using Inform,
554 but this section will introduce you to a few basic concepts to get your
555 bearings. The first line changes the working directory to
556 ``~/Inform/Games/MyGame1/``. The command ``cd`` (also known as ``chdir``,
557 short for "Change Directory to") lets you travel to the desired folder,
558 specified by the path, in this case: ``~/Inform/Games/MyGame1/``. The
559 ``~`` symbol stands for your home directory. That is, if your user name
560 were Dave, the above path is equal to::
562 /Users/Dave/Inform/Games/MyGame1/
564 You want to change that line so that it reads: ``cd
565 ~/Inform/Games/MyGame2/``
567 There are three parts to the second line:
569 1. ``inform630_macosx`` refers to the compiler program, and
570 ``../../Lib/Base`` is the name of the folder which contains it
571 (addressed relative to *this* folder, the one which holds the source
572 file). Double-dots stand for "go to the parent folder".
574 2. ``MyGame1`` is the name of the Inform source file; you don't need to
575 mention its extension of ``.inf`` if you don't want to. You'll want to
576 change this to match the name of your new file: ``MyGame2``.
578 3. ``+include_path=./,../../Lib/Base,../../Lib/Contrib`` tells the compiler
579 where to look for files like ``Parser`` and ``VerbLib`` which you've
580 Included in the source file (this may sound confusing now, but it will
581 make a lot of sense after you've delved a bit deeper into this Guide).
582 Three locations are suggested, separated by commas: this folder, which
583 holds the source file (``./``); the folder holding the standard library
584 files (``../../Lib/Base``); the folder holding useful bits and pieces
585 contributed by the Inform community (``../../Lib/Contrib``). The three
586 locations are searched in that order.
590 On the command line, you sometimes also see a compiler switch such as
591 ``-S``, used for controlling detailed aspects of how the compiler
592 operates. Rather than do that here, we find it more convenient to
593 place any necessary switches at the very top of the source file, as
594 we'll explain in the next chapter.
596 Once you've finished editing those lines, ``Save`` the file (not
597 ``SaveAs``), overwriting the original, and make sure that your text editor
598 doesn't append an extension like ``.txt`` (TextEdit, the default editor
599 that comes with OS X, is polite enough to ask you about this).
601 You'll need to have a new command file like this to match each new source
602 file which you create. The only item which will differ in the new file is
603 the name of the Inform source file -- ``MyGameN``. You must change this to
604 match the name of the new source file; everything else can stay the same in
605 each ``.command`` file that you create.
607 .. rubric:: Making your own command-line file
609 There are two peculiarities by which your system understands that
610 ``MyGame1.command`` is a Terminal Shell Script. One is the extension
611 ``.command``, and the other is an attribute of the file which marks it as
612 "executable" (the "executable bits"). If it doesn't meet both conditions,
613 ``MyGame1.command`` won't run as it should. You have to be careful when
614 editing this file: if you were, for instance, to open it in a text editor
615 and save it to a different location with a different name, the executable
616 bits might get lost, and when you double-click it, you would see:
618 .. image:: /images/mac_exec_error.*
621 To make a command file from scratch (also, to fix this problem) you can
624 1. Open any text editor and write (using your own path)::
626 cd ~/Inform/Games/MyGameN/
627 ../../Lib/Base/inform630_macosx MyGameN
628 +include_path=./,../../Lib/Base,../../Lib/Contrib
630 where ``MyGameN`` stands for the name you have chosen for your Inform
633 2. Save the file in the folder ``MyGameN`` and call it ``MyGameN.command``.
634 Make sure that the text editor doesn't append a ``.txt`` extension; if
635 it does, rename the file manually.
637 3. Go to ``Applications > Utilities`` and double-click on ``Terminal``.
638 This opens the utility which provides you with a set of windows to
639 access the UNIX command line. Supposing the computer is named Hal, and
640 the user Dave, you should see something like this::
642 Last login: Wed Jun 30 18:05:55 on ttyp1
646 4. Every time that you open a Terminal window, you're at your home
647 directory (as noted by the tilde after the computer's name). You can
648 travel to your working folder by typing::
650 cd Inform/Games/MyGameN
652 You'll see how the path changes::
654 [Hal:~/Inform/Games/MyGameN] Dave%
656 Now you can make the command file executable with::
658 chmod 777 MyGameN.command
660 5. Alternatively, you can omit the cd command if you give the full path to
663 chmod 777 ~/Inform/Games/MyGameN/MyGameN.command
665 This sets the executable bits for the file ``MyGameN.command``.
667 6. Close the Terminal window.
669 Now, every time you need to compile your game, you can just double-click on
670 ``MyGameN.command`` from the Finder.
672 .. rubric:: Getting a better editor
674 Although TextEdit is adequate when you're getting started, you'll find life
675 much easier if you obtain a more powerful editor program. We'd really like
676 to recommend one -- there's an exciting list of possibilities at
677 http://osx.hyperjeff.net/Apps/apps.php?sub=5 -- but at the time of writing
678 none of them seems outstandingly suited to IF authorship. If you find one
679 that works really well, please let us know.
681 .. rubric:: More about the editor
683 As well as the ones that we recommend, other good text editors are listed
684 at http://www.firthworks.com/roger/editors/. One feature that's well worth
685 looking out for is "hotkey compilation" -- being able to run the compiler
686 from *within* the editor. Another is "syntax colouring", where the editor
687 understands enough of Inform's syntax rules to colour-code your source
688 file; for example: red for brackets, braces and parentheses ``[ ]`` ``{ }``
689 and ``( )``, blue for reserved words like ``Object`` and ``print``, green
690 for items in quotes like '...' and "...", and so on. Syntax colouring is
691 of great assistance in getting your source file correct and thus avoiding
692 silly compilation errors.
694 .. rubric:: More about the compiler
696 The Inform compiler is a powerful but undramatic software tool; it does an
697 awful lot of work, but it does it all at once, without stopping to ask you
698 any questions. Its input is a readable text source file; the output is a
699 story file, also sometimes known as a **Z-code file** (because it contains
700 the game translated into code for the Z-machine, which we describe in the
703 If you're lucky, the compiler will translate your source file into Z-code;
704 perhaps surprisingly, it doesn't display any form of "success" message when
705 it succeeds. Often, however, it fails, because of mistakes which you've
706 made when writing the game. Inform defines a set of rules -- a capital
707 letter here, a comma there, these words only in a certain order, those
708 words spelled just so -- about which the compiler is extremely fussy. If
709 you accidentally break the rules, the compiler complains: it refuses to
710 write a Z-code file. *Do not worry about this*: the rules are easy to
711 learn, but just as easy to break, and all Inform designers inadvertently do
712 so on a regular basis. There's some additional information about dealing
713 with these mistakes, and about controlling how the compiler behaves, in
714 "Compiling your game" on page 189.
716 .. rubric:: More about the interpreter
718 One of the big advantages of the way Inform works is that a compiled game
719 -- the Z-code story file -- is portable between different computers.
720 That's not just from one PC to another: exactly the same story file will
721 run on a PC, a Mac, an Amiga, UNIX workstations, IBM mainframes, PalmOS
722 hand-helds, and on dozens of other past, present and future computers. The
723 magic that makes this happen is the interpreter program, a software tool
724 which pretends to be a simple computer called a **Z-machine**. The
725 Z-machine is an imaginary (or "virtual") computer, but its design has been
726 very carefully specified, so that an expert programmer can quite easily
727 build one. And that's exactly what has happened: a Macintosh guru has
728 built an Inform interpreter which runs on Apple Macs, a UNIX wizard has
729 built one for UNIX workstations, and so on. Sometimes, you even get a
730 choice; for popular machines like the PC and the Mac there are several
731 interpreters available. And the wonderful thing is: each of those
732 interpreters, on each of those computers, is able to play every Inform game
733 that's ever been written *and*, as a surprise bonus, all of the classic
734 1980s Infocom games like "Zork" and "The Hitchhiker's Guide to the Galaxy"
737 (Actually, that last sentence is a slight exaggeration; a few games are
738 very large, or have pictures included within them, and not all interpreters
739 can handle this. However, with that small pinch of salt, it's pretty
742 That's enough waffling: let's get started! It's time to begin designing
745 .. rubric:: Footnotes
748 "BSD" stands for Berkeley Software Distribution, the name of the UNIX
749 derivative distributed in the 1970s from the University of California,
750 Berkeley, and used collectively for the modern descendants of those