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$Revision: 1.1 $
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$Date: 1997/05/01 10:44:54 $
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20
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!!! README for gemtext. !!!
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If you think the above mentioned date is old check out
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http://stud.uni-sb.de/~gufl0000/atari/gemtext. You will find the latest
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version there. You will also find links to ftp sites from where you can
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download gemtext via anonymous ftp.
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See the file INSTALL for installing gemtext.
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See the file COPYING for licensing.
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See the file NEWS for information that is not covered by either this file
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or the provided manual pages. All information concerning features of
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gemtext included in any text file that comes along with this package is
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subject to change without notice!
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==========================================================================
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This is the gemtext package. The gemtext package offers standardized i18n
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(internationalization) features for GEM programs. The package is intended
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to help programmers to internationalize their programs. If you aren't a
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programmer you might want to read the file ABOUT-NLS to get an idea of
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national language support. But you won't need gemtext.
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GEM is a registered trademark of Digital Research Company. GEM is mainly
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used on Atari computers or the various emulations available today on other
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platforms. You can also find the so-called PC-GEM for IBM compatible
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machines. If you neither use an Atari nor emulate the Atari's OS you
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won't need gemtext too. Still it might be a good idea to have a look at
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the file ABOUT-NLS.
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All programs and libraries contained in this package will work on their
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own, only depending on some executables and libraries that can be found in
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most Unix-like environments. Yet, you will only benefit from gemtext if
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you have the GNU gettext package or another internationalization package
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that can be compared with gettext already installed. You will find the
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latest version of GNU gettext at
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ftp://prep.ai.mit.edu/pub/gnu
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It compiles without any problems with the GNU C-compiler and MiNTLib PL46.
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(Well, there's a little problem: If your msgfmt keeps on crashing with a
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bus error try to replace the module obstack.o in your MiNTLib with the
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obstack.c that comes along with GNU gettext. But this is a bug in the
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MiNTLib and not in GNU gettext.)
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In the following I will refer to any computer that can make use of
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xgemtext as 'Atari'. I also expect you to be familiar with the C
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programming language and with the well known data structures and function
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calls that are necessary for programming GEM applications.
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He, she, they... Quote from the gettext info file:
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"In this manual, we use *he* when speaking of the programmer or
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maintainer, *she* when speaking of the translator, and *they* when
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speaking of the installers or end users of the translated program.
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This is only a convenience for clarifying the documentation. It
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is *absolutely* not meant to imply that some roles are more
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appropriate to males or females. Besides, as you might guess, GNU
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`gettext' is meant to be useful for people using computers,
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whatever their sex, race, religion or nationality!"
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Last but not least: xgemtext is written in C++. Hence you will need a
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C++ compiler to compile the package. GNU C++ is a good choice if you
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don't already have one. If you don't have the system resources to run the
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compiler you will have to try to get an already compiled version. Good
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news: The library (which is the more important part of the gemtext
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package) is entirely written in plain C to allow easy porting to different
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compiler systems.
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CONTENTS
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========
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1. Why gemtext?
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2. Alternatives for i18n
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3. How to use the GNU gettext package
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4. How to use the gemtext package
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5. The library rintl
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6. Charsets: Atari versus ISO-Latin 1
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7. Miscellanea
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1. Why gemtext?
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===============
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The Atari's GUI (Graphical User Interface) offers possibilities for
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native language support for a long time already. All necessary graphical
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data and text for the user interface is usually kept in a so-called
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resource file. For example the program foobar.app will normally look for
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the resource file foobar.rsc in the same directory. A programmer aware of
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i18n will usually provide several of these resource file each of them
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containing the entire data in different languages, called e. g. en.rsc,
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fr.rsc, it.rsc and so on. The users have to rename the particular
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resource file in their language to foobar.rsc and the program will still
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behave the same but will display its messages in the chosen language.
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This procedere is suboptimal for various reasons.
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- The most obvious one is that you keep loads of redundant data in the
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extra provided resouce files. Usually the strings in the resource
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files occupy very little space in comparison to the graphical data.
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- GEM applications usually expect their resource files to reside at a
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fixed location and to have a fixed name. Hence, in a multi-user
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environment you have to choose one particular language for each
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application or you have to keep different copies of both your resource
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and other data files.
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- Once you have decided to include your resources into your source code
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you have to say goodbye to the idea of i18n.
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- Probably the most important disadvantage of the current system is the
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effort you have to take in updating your applications. Whenever you
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have changed the tree structure in your resource file you will have to
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edit every other resource file immediately if you do the translation
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yourself. If you let somebody else do your translations she will have
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enormous difficulties. She will have to click through the entire
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resource tree, taking care not to change the data structures
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unwillingly, and picking out the texts that have changed. If you
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haven't found some trickier system it is probably easier to restart the
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translation from the beginning.
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- Whenever your application has to display a message you have to edit
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your resource file even for little ones like:
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form_alert (1, "[1][ Memory exhausted! ][ Damned ]");
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Every string that has to be translated has to appear in the resource
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file. Considering that most resource file formats are restricted to 64
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kB of length and that most GEM libraries can handle only one single
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resource file this is often a severe restriction in the design of the
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GUI.
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2. Alternatives for i18n
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========================
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As far as programs are concerned that have to be run via a command line
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interpreter, there is already a portable, standardized system for message
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internationalization, the GNU gettext package. It offers tools for
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preparing all kinds of source files for i18n, tools that help both the
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programmer and translator to keep track of updated versions (and the
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maintainers, too) and it comes along with a free C library that gives
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access to the translated messages at runtime of the program depending on
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the setting of documented environment variables.
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You should get a copy of the GNU gettext package now. Yet, if you are too
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curious to download it at once, just go ahead but you might want to reread
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this file later as it refers to information that is available only with
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the GNU gettext package.
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The gemtext package should also be useful with NLS-packages (Native
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Language Support) other than GNU gettext to the degree that GNU gettext
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itself is compatible with other standardized packages. Yet, it has been
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only tested with GNU gettext as it is the only available one for Atari.
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3. How to use the GNU gettext package
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=====================================
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Forget about the whole GUI thing for a short while to get roughly an idea
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of programming with the GNU gettext package. We'll come back to the GUI
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shortly.
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NOTE: This section isn't meant to be an exhaustive description of the GNU
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gettext package. It is intended to give you an overview. If you already
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know the GNU gettext package you might safely skip this section.
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Localizing messages in a C program is very easily done. At first you need
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some (usually three) lines of extra code to tell the NLS library functions
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where to find the translated messages. Then you have to go through your
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code and decide for every string whether you want to get it translated or
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not. Strings that should be translated have to be embedded in a function
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call to gettext (). Thus instead of writing:
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printf ("Hello world!\n");
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you would now write
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printf (gettext ("Hello world!\n"));
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When you're fed up with typing g-e-t-t-e-x-t over and over again you will
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follow the habit of most of your colleagues and
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#define _(s) gettext (s)
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well knowing that now only three extra keystrokes will make the rest of
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the world happy.
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Very handy, very easy, isn't it? Unfortunately it doesn't work if you use
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strings for example in initialized structures or arrays. Really? Just to
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make sure that you don't abandon the whole thing already, I will tell you
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a secret: It still works! Read the gettext info file and follow the
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nodes Sources -> Special cases.
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After having marked all translatable strings in your sources you will want
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to extract them for translation by
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xgettext *.c
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producing a file messages.po that contains both the original strings and
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space for the translations. After the file being translated you will
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compile it into a binary by a call to the program msgfmt. This binary
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file will then usually be moved to
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/usr/(local/)share/locale/de/LC_MESSAGES/foobar.mo
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provided that your program has been translated into German ('de' is the
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ISO-639 2-letter country code for Germany).
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Now you set one of the envariables LANGUAGE, LANG or LC_ALL to 'de' and
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recompile your sources. Your linker will then complain about the
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reference to 'gettext' not being resolved and you will fix the problem by
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linking the program with the 'intl'-library that comes along with gettext
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(and gemtext, too). Surprise, surprise! Your program has learned to say
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hello to the world in yet another language.
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After long and satisfying experiences with your chef-d'oeuvre you might
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feel that it is not enough to say hello to the world. You want to say
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hello to the whole universe, too. So what now? Redo the whole thing?
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No! You simply update your sources and extract a new messages file.
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Before translating the file entirely again you should have msgmerge have a
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glimpse at both the original and the updated file. The program msgmerge
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is very clever and will probably guess what you have done. It will
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produce a new .po file that will already contain the strings you have
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translated the last time. It will also not cast away those strings that
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you do not care to translate any longer. It will comment them out
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instead, thus allowing you to change your mind again later. This feature
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is also very handy for corrected misspellings or minor modifications to
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strings. If msgmerge encounters such a case it will mark the maybe
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incorrect translation it guesses to be best as a "fuzzy" translation. If
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you agree with msgmerge, simply remove the "fuzzy" comment.
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Well, that's it in brief. Again, if you want to understand the GNU
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gettext package in its whole powerfulness you can't help reading the
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documentation.
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4. How to use the gemtext package
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=================================
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Probably you have already seen that it's no longer necessary to put
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strings for alert boxes or other free strings in your resource files.
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What has worked with printf will work with form_alert, too.
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And what about resources integrated in your source files? Why not? Most
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resource construction sets offer the possibility to produce a C source
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file as output and running a simple awk script on this file will already
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do the whole job for you. (An important advantage of integrated resources
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is that you're not restricted to 64 kB anymore).
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But if you don't bother to write all the routines to fix adresses of
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object trees and so on you will estimate the help of xgemtext from this
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package.
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Running
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xgemtext *.rsc
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in your source directory will extract all strings from your resource files
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placing them in a file messages.c looking more or less like this:
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/* This file was automatically produced by xgemtext <version> */
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#ifndef gettext_noop
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#define gettext_noop(s) (s)
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#endif
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const char* volatile nls_rsc_strings[] = {
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gettext_noop (" Foobar"),
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gettext_noop (" File"),
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gettext_noop (" Options"),
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gettext_noop (" About Foobar..."),
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gettext_noop (" Open"),
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... /* All other strings in your resource. */
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0L
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}
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It looks like a real C source file and it actually is one. Yet, usually
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you will never compile it nor link the corresponding object file. But you
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never know...
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Various options control xgemtext's behavior while extracting the strings
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from your resources, see the manual page for detailed information. Of
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course it does not extract only strings from objects of type G_TEXT,
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G_STRING etc. but from all kinds of objects containing text, including
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icons and bitmaps.
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So what's the purpose of messages.c if not compiling? You can run
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it (together with your other sources) through xgettext and now you have
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your resource strings in a .po file that can be processed with all the
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tools from the GNU gettext package.
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5. The library rintl
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====================
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Your resource file hasn't been patched by xgemtext. So, how to get the
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translated strings into the objects where they should go? You load your
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resource as usual. Now you simply have to take the habit to call
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gettree() for each object tree after fixing the object addresses via
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rsrc_gaddr(). The library function gettree() will walk thru the specified
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object tree replacing each pointer to a string with a pointer to the
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translated versions. It will also modify some members of the internal
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data structures (string length etc.) to the appropriate values.
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For simple objects this is all that you have to do. For more complicated
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ones translating the strings might leave your carefully designed objects a
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mess, beginning with menues. Remember that all string lengths may have
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been arbitrarily changed, resulting in objects that might hide each other
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or ugly looking gaps between objects that were meant to be close to each
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other.
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You will find numerous functions in the library rintl that will try to
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bring your objects back to a tolerable outer appearance again, each of
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them being called rnl<object_type>(). You will also find a function
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called rnltree() that will try to do the job for entire object trees. You
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can control the behavior of these adapt functions in numerous ways that
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should meet as many requirements as possible. You can specify spaces to
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be left between objects, margins to the tree borders, minimum widths of
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button objects and so on. You can also tell the functions not to walk
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thru the whole object tree but stopping at a certain level, thus allowing
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you to process different parts of your objects each with individual values
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for the control flags and variables.
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Menus usually require special treatment. rnlmenu() will usually to the
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job in a satisfying manner.
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As you might guess the result still can't be perfect. Your objects might
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need a little (or a whole lot of) fine tuning after being translated.
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Special care is also expected from the translator. She has to follow some
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simple rules while doing her job. You yourself, the programmer, should
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follow some rules when designing your object trees. The rnltree()
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function will work best if it finds all object children in rows and
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columns of constant height. This can be easily achieved by putting object
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children belonging logically together into visible or invisible boxes.
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For each library function you will find a manual page describing its
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functionality in detail.
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In the subdirectory ``example'' after building the binaries you will find
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a simple example program showing all this in a simple manner. Set the
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envariable LANGUAGE to one of the values de (German), it (Italian), fr
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(French), nl (Dutch), ga (Irish) or pt (portuguese) to select
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your preferred language. Setting the envariable to an unknown
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value will make the example program choose the default values
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``C'' (in this case English).
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Select the menu entry ``International...'' to see a simple text displayed
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in your selected language. The entry ``Language...'' might allow you to
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change the language even at runtime but this depends on the existence of
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the putenv() function in your standard C library. If putenv() is not
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found the entry will be disabled. You have to change the language on the
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command line.
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In the ``Options'' menu you can follow the metamorphosis of a GEM dialog,
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first without any treatment, then after a call to rnltree() and finally
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after some additional beauty cures. See the source and the manual
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pages rnltree(3) and rnlpush(3) for details.
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6. Charsets: Atari versus ISO-Latin 1
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=====================================
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There's a dilemma with the i18n thing. On other platforms (especially of
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the workstation sector) you can not only localize the language but also
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the charset to utilize. AFAIK there's no C library available that allows
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you to do so on Atari.
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A couple of years ago there was but one choice for a charset in the Atari
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sector, the charset of the Atari's built-in system font. Now more and
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more Atari users have switched to the universally used ISO-Latin 1 charset
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also known as i-8859-1, especially when using a command line interpreter.
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If you use already internationalized GNU packages you will come across
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this charset, too. (Note that both ISO-Latin 1 and the Atari charset are
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intended for use with western european languages, the Atari's charset
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to a certain extent also for Hebrew and Greek. Hence the following refers
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only to those languages).
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I have chosen the following way: As it is very unlikely that you use an
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ISO-Latin 1 charset with GEM, the files containing the messages for the
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example program - which has a GUI - have to be read with the Atari
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charset. But these files shouldn't go into your locale directory. The
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whole thing is provided as an example and should stay where it is (i. e.
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it isn't installed).
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For xgemtext you have the choice. If you use an ISO-Latin-1 font (as you
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should do) simply follow the instructions in ABOUT-NLS. If you insist on
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using a font with an Atari codeset set the environment variable LANGUAGE
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(or LC_ALL or LC_xxx) to <ll>.atarist where <ll> should specify the
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language you want to use. When installing xgemtext the appropriate
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directories in your locale directory get created. They will be called
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<localedir>/<ll>.atarist/LC_MESSAGES.
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7. Miscellanea
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==============
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Now something that might leave you a little uneasy: The translating
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project relies on the original programs being written in English. Say you
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have written your program in Rhaeto-Romance and you want to have it
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translated into Irish. Well, the diligent translator from the Aron
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Islands is lucky enough to understand English and she probably won't
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bother to learn Rhaeto-Romance. The only possibility to solve the problem
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is to agree upon one base language and this language is English. If you
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have made it until here through this document I'm sure you will manage to
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write the messages in your sources and resources in English, too.
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Of course you will have to explain your users how to benefit from the new
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i18n features of your program. Include the file ABOUT-NLS that is part
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of the GNU gettext distribution. This will tell your users the
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necessary measures to take.
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You should also include a copy of the file ATARI.NLS in your sources.
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This file is intended to be read by translators. They will find some
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useful hints for translating messages for GEM programs.
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Note that gemtext is *not* part of the GNU project! Bug reports,
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comments, compliments should be sent to the author, flames and criticism
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to /dev/null. Please also note that everything you find in the directory
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intl *is* part of the GNU gettext package. Thus, any comments concerning
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files in this subdirectory should be directed to the maintainer of the GNU
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gettext package. There are some other files that consist partly or
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entirely of copyrighted material by the Free Software Foundation. If in
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doubt check the header texts.
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Hope you have fun with gemtext!
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Guido Flohr <gufl0000@stud.uni-sb.de>.
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