7 | *C was a captain, all covered with lace;*
8 | *D was a drunkard, and had a red face.*
12 .. image:: /images/picC.png
19 onventional -- static -- fiction can be written using nothing more than
20 pencil and paper, or typewriter, or word-processor; however, the
21 requirements for producing IF are a little more extensive, and the creative
22 process slightly more complex.
24 * For static fiction, you first write the text, and then you check it by
25 reading what you've written.
27 * For IF, you still have to write all of the text, but you also have to
28 establish what text gets displayed when. Once you have written the
29 necessary Inform instructions, you use a **compiler** program to convert
30 them into a playable format. The resulting information is played by an
31 **interpreter** program, which permits you to interact with your
34 With static fiction What You Write Is What You Read, but with IF the format
35 in which you initially write the game doesn't bear much resemblance to the
36 text which the interpreter ultimately displays. For example, the "William
37 Tell" game, in the form that we wrote it, starts like this:
39 .. code-block:: inform6
41 !============================================================================
42 Constant Story "William Tell";
44 "^A simple Inform example
45 ^by Roger Firth and Sonja Kesserich.^";
50 !============================================================================
58 You will never need to look at it in the form produced by the compiler::
60 050000012C6C2C2D1EF6010A0C4416900010303230313031004253FEA90C0000
61 0000000000000000000000000000168F000000000000010200000000362E3231
64 but, as you'll notice from the full transcript in "William Tell" story on
65 page 219, the player will see the following::
67 The place: Altdorf, in the Swiss canton of Uri. The year is 1307, at
68 which time Switzerland is under rule by the Emperor Albert of
69 Habsburg. His local governor -- the vogt -- is the bullying Hermann
70 Gessler, who has placed his hat atop a wooden pole in the centre of
71 the town square; everybody who passes through the square must bow to
72 this hated symbol of imperial might...
74 Clearly, there's more to writing IF than just laying down the words in the
75 right order. Fortunately, we can make one immediate simplification: the
76 translated form produced by the Inform compiler -- those cryptic numbers
77 and letters held in what's known as the **story file** -- is designed to be
78 read by the interpreter program. The story file is an example of a
79 "binary" file, containing data intended for use only by a computer program.
80 Forget all that unreadable gibberish.
82 So that leaves just the first form -- the one starting "``Constant Story``"
83 -- which represents the tale written as a piece of IF. That's the **source
84 file** (so called because it contains the game in its original, source,
85 form) which you create on your computer. The source file is a "text" (or
86 "ASCII") file containing words and phrases which can be read -- admittedly
87 after a little tuition, which is what this guide is all about -- by humans.
89 How do you create that source file? Using a third software program: an
90 **editor**. However, unlike the compiler and interpreter, this program
91 isn't dedicated to the Inform system -- or even to IF. An editor is an
92 entirely general tool for creating and modifying text files; you've
93 probably already got a basic one on your computer (an IBM PC running
94 Windows comes with NotePad, while an Apple Macintosh has SimpleText or
95 TextEdit), or you can download a better one from the Internet. An editor
96 is like a word-processing program such as MS Word, only much less complex;
97 no fancy formatting features, no bold or italics or font control, no
98 embedded graphics; it simply enables you to type lines of text, which is
99 exactly what's needed to create an IF game.
101 If you look at the game source on the previous page, or in the "William
102 Tell" story on page 219, you'll notice ``Include "Parser";`` and ``Include
103 "VerbLib";`` a few lines down from the top of the file. These are
104 instructions to the Inform compiler to "include" -- that is, to merge in
105 the contents -- of files called ``Parser.h`` and ``VerbLib.h``. These are
106 not files which you have to create; they're standard **library files**,
107 part of the Inform system. All that you have to do is remember to Include
108 them in every game that you write. Until you've a fair understanding of
109 how Inform works, you've no need to worry about what they contain (though
110 you can look if you want to: they're readable text files, just like the
111 ones this guide will teach you to write).
113 So, we've now introduced all of the bits and pieces which you need in order to
114 write an Inform adventure game:
116 * a text **editor** program which can create and modify the **source file**
117 containing the descriptions and definitions of your game. Although it's
118 not recommended, you can even use a word-processing program to do this,
119 but you have to remember to save your game in Text File format;
121 * some Inform **library files** which you Include in your own game source
122 file in order to provide the model world -- a basic game environment and
123 lots of useful standard definitions;
125 * the Inform **compiler** program, which reads your source file (and the
126 library files) and translates your descriptions and definitions into
127 another format -- the **story file** -- intended only for...
129 * an Inform **interpreter** program, which is what players of your game
130 use. A player doesn't require the source file, library files or compiler
131 program, just the interpreter and the game in compiled format (which,
132 because it's a binary file not meaningful to human eyes, neatly
133 discourages players from cheating).
135 All of those, apart from the editor, can be downloaded for free from the IF
136 Archive. One approach is to fetch them individually, following the
137 guidance on Graham's page: visit http://www.inform-fiction.org/ and look
138 for the "Software" section. However, if you're using a PC or a Mac, you'll
139 find it easier to download a complete package containing everything that
140 you need to get started.
142 Inform on an IBM PC (running Microsoft Windows)
143 ===============================================
145 Although the Windows operating system is upgraded on a fairly regular
146 basis, its basic capabilities and ways of working have remained
147 more-or-less consistent for many years. The information here applies to
148 PCs running Windows 95 onwards.
150 .. rubric:: Installing and testing Inform
154 1. Download http://www.firthworks.com/roger/downloads/inform_pc_env.zip to
155 a temporary location on your PC.
157 2. Use a tool like WinZip to unzip the downloaded file, giving you a new
158 ``Inform`` folder. Move this folder (and its contents) to a suitable
159 location on your PC -- a good place would be ``C:\My Documents\Inform``,
160 but you could also use ``C:\Documents and Settings\yourname\My
161 Documents\Inform``, ``C:\Inform`` or ``C:\Program Files\Inform``. You
162 should now have this set of folders:
164 .. image:: /images/inform_pc_env.*
167 In order to make the download small and fast, these folders include just
168 enough to get you started as an Inform designer -- the compiler and
169 interpreter programs, the library files, the ``Ruins.inf`` example file
170 from the *Inform Designer's Manual*, and a template for your own first
171 game. A few other folders are included as placeholders where you could
172 later download additional components, if you wanted them. As soon as
173 possible, you should download the *Inform Designer's Manual* into the
174 ``Inform\Doc`` folder -- it's an essential document to have, and has
175 been omitted from this download only because of its 3MB size.
177 3. To verify that the downloaded files work properly, use Windows Explorer
178 to display the contents of the ``Inform\Games\MyGame1`` folder: you will
179 see the two files ``MyGame1.bat`` and ``MyGame1.inf``:
181 .. image:: /images/filelist1.*
184 ``MyGame1.inf`` is a tiny skeleton game in Inform source format. By
185 convention, all Inform source files have an extension of .inf; Windows
186 has an inbuilt definition for ``.inf`` files, and so shows its Type as
187 "Setup Information", but this doesn't seem to matter. If you
188 double-click the file, it should open in NotePad so that you can see how
189 it's written, though it probably won't mean much -- yet.
191 4. ``MyGame1.bat`` is an MS-DOS batch file (an old kind of text-only
192 computer program, from the days before point-and-click interfaces) which
193 runs the Inform compiler. Double-click it; a DOS window opens as the
194 game compiles, and you'll see this::
196 C:\My Documents\Inform\Games\MyGame1>..\..\Lib\Base\Inform MyGame1
197 +include_path=.\,..\..\Lib\Base,..\..\Lib\Contrib | more
199 Inform 6.30 for Win32 (27th Feb 2004)
201 C:\My Documents\Inform\Games\MyGame1>pause "at end of compilation"
202 Press any key to continue . . .
204 Press the space bar, then close the DOS window.
208 On Windows NT, 2000 and XP, the DOS window closes of its own accord
209 when you press the space bar.
211 5. A story file ``MyGame1.z5`` has appeared in the folder; this is the
212 compiled game, which you can play using an interpreter:
214 .. image:: /images/filelist2.*
217 The extension of ``.z5`` signifies that the story file contains a
218 Z-machine game in Version 5 (today's standard) format.
220 6. Use Windows Explorer to display the contents of the ``Inform\Bin\Frotz``
221 folder, and double-click ``Frotz.exe``; the interpreter presents an
222 ``Open a Z-code Game`` dialog box.
224 7. Browse to display the ``Inform\Games\MyGame1`` folder, and select
225 ``MyGame1.z5``. Click ``Open``. The game starts running in the Windows
228 8. When you tire of "playing" the game -- which won't take long -- you can
229 type the QUIT command, you can select ``File > Exit``, or you can simply
230 close the Frotz window.
232 9. Using the same techniques, you can compile and play ``Ruins.inf``, which
233 is held in the ``Inform\Games\Download`` folder. RUINS is the game used
234 as an example throughout the *Inform Designer's Manual*.
236 .. rubric:: Setting file associations
238 The business of first starting the interpreter, and then locating the story
239 file that you want to play, is clumsy and inconvenient. Fortunately, when
240 you first run the Frotz interpreter, it automatically creates an
241 association with story files whose extension is ``.z5``. From now on,
242 you'll be able to play a game simply by double-clicking its story file. If
243 some any reason this doesn't work, you can set up the association yourself:
245 1. Double-click ``MyGame1.z5``; Windows asks you to select the program
248 * type ``Z-code V5 Adventure`` as the "``Description for...``"
249 * click to select "``Always use this program...``"
252 2. Browse to display the ``Inform\Bin\Frotz`` folder, and select
253 ``Frotz.exe``. Click ``Open``.
255 .. rubric:: Changing the Windows icon
257 If the Windows icon that's displayed alongside ``MyGame1.z5`` doesn't look
258 right, you can change it.
260 1. In Windows Explorer, either select ``View > Options...`` and click
261 ``File Types``, or select ``Tools > Folder Options...`` and click ``File
264 * select the game file type in the list, which is in order either of
265 application (Frotz) or of extension (Z5)
268 2. In the ``Edit File Type`` dialog, click ``Change Icon``.
270 3. In the ``Change Icon`` dialog, ensure that the file name is
271 ``Inform\Bin\Frotz\Frotz.exe``, and select one of the displayed icons.
272 Click ``OK`` to close all the dialogs. The files in the folder should
275 .. image:: /images/filelist3.*
278 .. rubric:: Compiling using a batch file
280 You can view -- and of course change -- the contents of ``MyGame1.bat``,
281 the batch file which you double-click to run the compiler, using any text
282 editor. You'll see two lines, something like this (the first chunk is all
283 on one long line, with a space between the ``MyGame1`` and the
286 ..\..\Lib\Base\Inform MyGame1
287 +include_path=.\,..\..\Lib\Base,..\..\Lib\Contrib | more
288 pause "at end of compilation"
290 These long strings of text are command lines -- a powerful interface method
291 predating the icons and menus that most computer users know. You won't
292 need to master the command line interface in order to start using Inform,
293 but this section will tell you what these particular command lines are
294 doing. There are four parts to the first line:
296 1. ``Inform`` refers to the compiler program, and ``..\..\Lib\Base`` is the
297 name of the folder which contains it (addressed relative to *this*
298 folder, the one which holds the source file). Double-dots stand for "go
299 to the parent folder".
301 2. ``MyGame1`` is the name of the Inform source file; you don't need to
302 mention its extension of ``.inf`` if you don't want to.
304 3. ``+include_path=.\,..\..\Lib\Base,..\..\Lib\Contrib`` tells the compiler
305 where to look for files like ``Parser`` and ``VerbLib`` which you've
306 Included. Three locations are suggested: this folder, which holds the
307 source file (``.\``); the folder holding the standard library files
308 (``..\..\Lib\Base``); the folder holding useful bits and pieces
309 contributed by the Inform community (``..\..\Lib\Contrib``). The three
310 locations are searched in that order.
314 On the command line, you sometimes also see a compiler **switch**
315 such as ``-S``, used for controlling detailed aspects of how the
316 compiler operates. Rather than do that here, we find it more
317 convenient to place any necessary switches at the very top of the
318 source file, as we'll explain in the next chapter.
320 4. ``| more`` causes the compiler to pause if it finds more mistakes than
321 it can tell you about on a single screen, rather than have them scroll
322 off the top of the MS-DOS window. Press the space bar to continue the
325 The second line -- ``pause "at end of compilation"`` -- just prevents the
326 window from closing before you can read its contents, as it otherwise would
327 on Windows NT, 2000 and XP.
329 You'll need to have a new batch file like this to match each new source
330 file which you create. The only item which will differ in the new file is
331 the name of the Inform source file -- ``MyGame1`` in this example. You
332 must change this to match the name of the new source file; everything else
333 can stay the same in each ``.bat`` file that you create.
335 .. rubric:: Getting a better editor
337 Although NotePad is adequate when you're getting started, you'll find life
338 much easier if you obtain a more powerful editor program. We recommend
339 TextPad, available as shareware from http://www.textpad.com/; in addition,
340 there are some detailed instructions at
341 http://www.onyxring.com/informguide.aspx?article=14 on how to improve the
342 way that TextPad works with Inform. The biggest single improvement, the
343 one that will make game development dramatically simpler, is being able to
344 compile your source file *from within* the editor. No need to save the
345 file, switch to another window and double-click the batch file (and indeed,
346 no further need for the batch file itself): just press a key while editing
347 the file -- and it compiles there and then. You can also run the
348 interpreter with similar ease. The convenience of doing this far outweighs
349 the small amount of time needed to obtain and configure TextPad.
351 Inform on an Apple Macintosh (running OS X)
352 ===========================================
354 Whereas our instructions for using Inform on a PC apply to just about all
355 versions of Windows, on the Macintosh we need to be more precise. Our
356 guidance here is specifically for Mac OS X, rather than for its predecessor
357 OS 9, and it may be helpful if we first mention a few relevant differences.
359 Mac OS X is a robust system constructed around -- or on top of -- BSD
360 [#bsd]_ UNIX. There are several kinds of applications that will run on
363 * Aqua: specifically designed for the Graphical User Interface of Mac OS X,
364 and taking advantage of its underlying technologies. Broadly, there
365 are two types of Aqua application:
367 * Cocoa: built with programming tools designed for Mac OS X.
369 * Carbon: built with the programming tools designed for Mac OS 9 and
370 earlier versions, but "translated" to take advantage of OS X.
372 * Classic: designed to work on Mac OS 9 and earlier versions. They need to
373 run in the Classic environment of OS X; roughly speaking, Classic is an
374 emulation of the older Mac systems.
376 * X11: based on a windowing system designed for the UNIX/Linux world. They
377 need an X-Windows server to run, and their appearance and functionality
378 may seem a lot different to what the Aqua user expects.
380 * UNIX: most UNIX programs (including Linux) will run on your Mac OS X, but
381 they usually have to be accessed (or configured) from the UNIX core of
382 your Mac, through the Terminal utility.
384 These differences may be significant, since some of the tools designed to
385 develop and run IF on a Mac system (for example, ones you'll find in the
386 Archive) have been built by programmers working in different environments
387 with varying technologies. We have tried to select tools that will make
388 your life easy as a beginner, but in time you may want to investigate
389 alternative approaches.
391 .. rubric:: Installing and testing Inform
395 1. Download http://www.firthworks.com/roger/downloads/inform_macosx_env.sit
396 to a temporary location on your Mac.
398 2. Use a tool like StuffIt Expander to unpack the downloaded file (if your
399 system configuration is standard, a mere double-click will make it
400 self-extract at the current location, if it hasn't already expanded all
401 by itself). You'll now have a new ``Inform`` folder. Move this folder
402 (and its contents) to a suitable location in your Mac.
406 It is a good idea for now to place it in your home directory;
407 otherwise, a few pre-configured items may not work as explained.
408 Once you learn the basics of the configuration, you may move the
409 Inform folder to a different location and hack all the defaults like
410 the professionals do.
412 You should now have this set of folders:
414 .. image:: /images/inform_mac_env.*
417 In order to make the download small and fast, these folders include just
418 enough to get you started as an Inform designer -- the compiler and
419 interpreter programs, the library files, the ``Ruins.inf`` example from
420 the *Inform Designer's Manual*, and a template for your own first game,
421 which you may copy and rename each time you begin a new Inform project.
422 A few other folders are included as placeholders where you could later
423 download additional components, if you wanted them. As soon as
424 possible, you should download the *Inform Designer's Manual* into the
425 ``Inform/Doc`` folder -- it's an essential document to have, and has
426 been omitted from this download only because of its 3MB size.
428 3. To verify that the downloaded files work properly, use the Finder to
429 display the contents of the ``Inform/Games/MyGame1`` folder: you will see
430 the files ``MyGame1.command`` and ``MyGame1.inf``:
432 .. image:: /images/mac_filelist1.*
435 ``MyGame1.inf`` is a tiny skeleton game in Inform source format. By
436 convention, all Inform source files have an extension of ``.inf``.
437 However, Mac OS X may show its Kind as "FUJI BAS IMG document", and try
438 to open it with GraphicConverter. If you're not a regular user of FUJI
439 BAS IMG documents, you'll probably want to change this. Either:
441 * right-click on the file (or Ctrl-click)
443 * select ``Open with`` and choose ``Other...``
445 * in the ``Open with`` dialog, go to the ``Applications`` folder and
448 * click to select "``Always open with``"
454 * right-click on the file (or Ctrl-click)
456 * press Option, select ``Always open with`` and choose ``Other...``
458 * in the ``Open with`` dialog, go to the ``Applications`` folder and
463 Now, if you double-click the file, it should open in TextEdit so that
464 you can see how it's written, though it probably won't mean much -- yet.
466 The above process may affect only this specific file. To change the
467 program that opens by default all ``.inf`` files, try this:
469 * right-click on the file (or Ctrl-click)
471 * select ``Get Info``
473 * in the ``Open with`` tab, select TextEdit as the application
475 * click the ``Change All...`` button, and confirm the change when asked.
477 4. ``MyGame1.command`` is a Terminal Shell Script (a UNIX executable
478 command-line file, a kind of text-only computer program from the days
479 before point-and-click interfaces) which runs the Inform compiler.
480 Double-click it; a UNIX window opens as the game compiles, and you'll
481 see something like this (the working path will reflect your folder
484 Last login: Sat Jul 3 03:07:51 on ttyp1
486 /Users/Dave/Inform/Games/MyGame1/MyGame1.command; [Hal:~] Dave%
487 /Users/Dave/Inform/Games/MyGame1/MyGame1.command; exit
488 Inform 6.30 (27th Feb 2004)
494 Verify this output. It's what's in the PDF, but the command prompt
495 looks like it's in the wrong place.
497 5. A story file ``MyGame1.z5`` has appeared in the folder; this is the
498 compiled game, which you can play using an interpreter:
500 .. image:: /images/mac_filelist2.*
503 The extension of ``.z5`` signifies that the story file contains a
504 Z-machine game in Version 5 (today's standard) format.
506 6. Use the Finder to display the contents of the ``Inform/Bin/Zoom``
507 folder, and double-click ``Zoom``; the interpreter presents an ``Open``
510 7. Browse to display the ``Inform/Games/MyGame1`` folder, and select
511 ``MyGame1.z5``. Click ``Open``. The game starts running in the Zoom
514 8. When you tire of "playing" the game -- which won't take long -- you can
515 type the QUIT command, you can select ``Zoom > Quit Zoom``, or you can
516 simply close the Zoom window.
518 .. rubric:: Setting file associations
520 The business of first starting the interpreter, and then locating the story
521 file that you want to play, is clumsy and inconvenient. Fortunately, when
522 the system first "sees" the Zoom interpreter (which is a nice Aqua
523 application) it automatically creates an association with story files whose
524 extension is ``.z5`` (and with other Infocom formats). From now on, you'll
525 be able to play a game simply by double-clicking its story file.
527 The files in the folder should now look like this:
529 .. image:: /images/mac_filelist3.*
532 .. rubric:: Compiling using a command-line file
534 If you have followed these instructions to configure your system, every
535 time that you need to compile your source code you just have to
536 double-click on the file ``MyGame1.command``. However, this file is good
537 only for this folder and for ``MyGame1.inf``.
539 If you want to start coding another game, you may copy the folder
540 ``MyGame1`` with all its contents and rename it as you please (for example,
541 ``MyGame2`` or something more appropriate). Inside the folder, you'll also
542 want to rename the relevant files:
544 ``MyGame1.inf`` might become ``MyGame2.inf``, or ``MobyDick.inf``,
547 ``MyGame1.command`` would change to match: ``MyGame2.command``, or
548 ``MobyDick.command``.
550 You can view -- and of course change -- the contents of
551 ``MyGame2.command``, the command file which you double-click to run the
552 compiler, using any text editor. You'll see two lines, something like this
553 (the second chunk is all on one long line, with a space between the
554 ``MyGame1`` and the ``+include_path``)::
556 cd ~/Inform/Games/MyGame1/
557 ../../Lib/Base/inform630_macosx MyGame1
558 +include_path=./,../../Lib/Base,../../Lib/Contrib
560 These long strings of text are command lines -- a powerful interface method
561 predating the icons and menus that most computer users know. You won't
562 need to master the command line interface in order to start using Inform,
563 but this section will introduce you to a few basic concepts to get your
564 bearings. The first line changes the working directory to
565 ``~/Inform/Games/MyGame1/``. The command ``cd`` (also known as ``chdir``,
566 short for "Change Directory to") lets you travel to the desired folder,
567 specified by the path, in this case: ``~/Inform/Games/MyGame1/``. The
568 ``~`` symbol stands for your home directory. That is, if your user name
569 were Dave, the above path is equal to::
571 /Users/Dave/Inform/Games/MyGame1/
573 You want to change that line so that it reads: ``cd
574 ~/Inform/Games/MyGame2/``
576 There are three parts to the second line:
578 1. ``inform630_macosx`` refers to the compiler program, and
579 ``../../Lib/Base`` is the name of the folder which contains it
580 (addressed relative to *this* folder, the one which holds the source
581 file). Double-dots stand for "go to the parent folder".
583 2. ``MyGame1`` is the name of the Inform source file; you don't need to
584 mention its extension of ``.inf`` if you don't want to. You'll want to
585 change this to match the name of your new file: ``MyGame2``.
587 3. ``+include_path=./,../../Lib/Base,../../Lib/Contrib`` tells the compiler
588 where to look for files like ``Parser`` and ``VerbLib`` which you've
589 Included in the source file (this may sound confusing now, but it will
590 make a lot of sense after you've delved a bit deeper into this Guide).
591 Three locations are suggested, separated by commas: this folder, which
592 holds the source file (``./``); the folder holding the standard library
593 files (``../../Lib/Base``); the folder holding useful bits and pieces
594 contributed by the Inform community (``../../Lib/Contrib``). The three
595 locations are searched in that order.
599 On the command line, you sometimes also see a compiler switch such as
600 ``-S``, used for controlling detailed aspects of how the compiler
601 operates. Rather than do that here, we find it more convenient to
602 place any necessary switches at the very top of the source file, as
603 we'll explain in the next chapter.
605 Once you've finished editing those lines, ``Save`` the file (not
606 ``SaveAs``), overwriting the original, and make sure that your text editor
607 doesn't append an extension like ``.txt`` (TextEdit, the default editor
608 that comes with OS X, is polite enough to ask you about this).
610 You'll need to have a new command file like this to match each new source
611 file which you create. The only item which will differ in the new file is
612 the name of the Inform source file -- ``MyGameN``. You must change this to
613 match the name of the new source file; everything else can stay the same in
614 each ``.command`` file that you create.
616 .. rubric:: Making your own command-line file
618 There are two peculiarities by which your system understands that
619 ``MyGame1.command`` is a Terminal Shell Script. One is the extension
620 ``.command``, and the other is an attribute of the file which marks it as
621 "executable" (the "executable bits"). If it doesn't meet both conditions,
622 ``MyGame1.command`` won't run as it should. You have to be careful when
623 editing this file: if you were, for instance, to open it in a text editor
624 and save it to a different location with a different name, the executable
625 bits might get lost, and when you double-click it, you would see:
627 .. image:: /images/mac_exec_error.*
630 To make a command file from scratch (also, to fix this problem) you can
633 1. Open any text editor and write (using your own path)::
635 cd ~/Inform/Games/MyGameN/
636 ../../Lib/Base/inform630_macosx MyGameN
637 +include_path=./,../../Lib/Base,../../Lib/Contrib
639 where ``MyGameN`` stands for the name you have chosen for your Inform
642 2. Save the file in the folder ``MyGameN`` and call it ``MyGameN.command``.
643 Make sure that the text editor doesn't append a ``.txt`` extension; if
644 it does, rename the file manually.
646 3. Go to ``Applications > Utilities`` and double-click on ``Terminal``.
647 This opens the utility which provides you with a set of windows to
648 access the UNIX command line. Supposing the computer is named Hal, and
649 the user Dave, you should see something like this::
651 Last login: Wed Jun 30 18:05:55 on ttyp1
655 4. Every time that you open a Terminal window, you're at your home
656 directory (as noted by the tilde after the computer's name). You can
657 travel to your working folder by typing::
659 cd Inform/Games/MyGameN
661 You'll see how the path changes::
663 [Hal:~/Inform/Games/MyGameN] Dave%
665 Now you can make the command file executable with::
667 chmod 777 MyGameN.command
669 5. Alternatively, you can omit the cd command if you give the full path to
672 chmod 777 ~/Inform/Games/MyGameN/MyGameN.command
674 This sets the executable bits for the file ``MyGameN.command``.
676 6. Close the Terminal window.
678 Now, every time you need to compile your game, you can just double-click on
679 ``MyGameN.command`` from the Finder.
681 .. rubric:: Getting a better editor
683 Although TextEdit is adequate when you're getting started, you'll find life
684 much easier if you obtain a more powerful editor program. We'd really like
685 to recommend one -- there's an exciting list of possibilities at
686 http://osx.hyperjeff.net/Apps/apps.php?sub=5 -- but at the time of writing
687 none of them seems outstandingly suited to IF authorship. If you find one
688 that works really well, please let us know.
690 .. rubric:: More about the editor
692 As well as the ones that we recommend, other good text editors are listed
693 at http://www.firthworks.com/roger/editors/. One feature that's well worth
694 looking out for is "hotkey compilation" -- being able to run the compiler
695 from *within* the editor. Another is "syntax colouring", where the editor
696 understands enough of Inform's syntax rules to colour-code your source
697 file; for example: red for brackets, braces and parentheses ``[ ]`` ``{ }``
698 and ``( )``, blue for reserved words like ``Object`` and ``print``, green
699 for items in quotes like '...' and "...", and so on. Syntax colouring is
700 of great assistance in getting your source file correct and thus avoiding
701 silly compilation errors.
703 .. rubric:: More about the compiler
705 The Inform compiler is a powerful but undramatic software tool; it does an
706 awful lot of work, but it does it all at once, without stopping to ask you
707 any questions. Its input is a readable text source file; the output is a
708 story file, also sometimes known as a **Z-code file** (because it contains
709 the game translated into code for the Z-machine, which we describe in the
712 If you're lucky, the compiler will translate your source file into Z-code;
713 perhaps surprisingly, it doesn't display any form of "success" message when
714 it succeeds. Often, however, it fails, because of mistakes which you've
715 made when writing the game. Inform defines a set of rules -- a capital
716 letter here, a comma there, these words only in a certain order, those
717 words spelled just so -- about which the compiler is extremely fussy. If
718 you accidentally break the rules, the compiler complains: it refuses to
719 write a Z-code file. *Do not worry about this*: the rules are easy to
720 learn, but just as easy to break, and all Inform designers inadvertently do
721 so on a regular basis. There's some additional information about dealing
722 with these mistakes, and about controlling how the compiler behaves, in
723 "Compiling your game" on page 189.
725 .. rubric:: More about the interpreter
727 One of the big advantages of the way Inform works is that a compiled game
728 -- the Z-code story file -- is portable between different computers.
729 That's not just from one PC to another: exactly the same story file will
730 run on a PC, a Mac, an Amiga, UNIX workstations, IBM mainframes, PalmOS
731 hand-helds, and on dozens of other past, present and future computers. The
732 magic that makes this happen is the interpreter program, a software tool
733 which pretends to be a simple computer called a **Z-machine**. The
734 Z-machine is an imaginary (or "virtual") computer, but its design has been
735 very carefully specified, so that an expert programmer can quite easily
736 build one. And that's exactly what has happened: a Macintosh guru has
737 built an Inform interpreter which runs on Apple Macs, a UNIX wizard has
738 built one for UNIX workstations, and so on. Sometimes, you even get a
739 choice; for popular machines like the PC and the Mac there are several
740 interpreters available. And the wonderful thing is: each of those
741 interpreters, on each of those computers, is able to play every Inform game
742 that's ever been written *and*, as a surprise bonus, all of the classic
743 1980s Infocom games like "Zork" and "The Hitchhiker's Guide to the Galaxy"
746 (Actually, that last sentence is a slight exaggeration; a few games are
747 very large, or have pictures included within them, and not all interpreters
748 can handle this. However, with that small pinch of salt, it's pretty
751 That's enough waffling: let's get started! It's time to begin designing
754 .. rubric:: Footnotes
757 "BSD" stands for Berkeley Software Distribution, the name of the UNIX
758 derivative distributed in the 1970s from the University of California,
759 Berkeley, and used collectively for the modern descendants of those