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[10]Interesting internationalization

   Posted on September 18, 2008
   Filed Under [11]Programming |

   I've been having a rather enjoyable discussion with [12]Lorenzo
   Bettini, the author of GNU [13]Gengetopt and [14]Gengen. If you are not
   familiar with Gengetopt, its a tool that simplifies generating the code
   required for programs to accept options. I [15]talked about gengetopt a
   while back on this blog.

   The discussion surrounds support for internationalization, which simply
   means a program printing output in whatever language your system is
   using. A very popular means to accomplish this is the GNU gettext
   library, or its counterpart in various other operating systems.
   Disclamer, if you do not care about C standards and common UNIX
   programming, this post will probably bore you to tears. However, your
   welcome to read on if only to discover how much I value life in boring
   geeky flavors :)

   Recently, while working on HelenOS I found the need to implement
   getopt. I'm working on something a lot like busybox, but from scratch.
   Rather than re-invent the getopt wheel yet again, I dove into the
   source code of GNU getopt as well as the various *BSD implementations
   to find the one that was easiest to port. One thing that stood out at
   me was that most implementations declared error strings and formats as
   static, English strings.

   A week later, a proposal to add gettext support came across the
   gengetopt mailing list. I voted to not include it because the resulting
   output would be at best mixed, as error strings in basic C89/C99 libc
   are hard coded, usually in English. The getopt family of functions are
   an interesting corner case, most core libc functions never print
   anything ... they just exit with some value and set a global errno to
   inform the calling function of what went wrong. Its then up to the
   calling function to (use or not use) something like gettext to display
   the information in the appropriate language.

   This got me thinking .. if we're making a truly modern operating system
   based on C89/C99 .. internationalization must be easy to leverage.
   Talking with Lorenzo, some interesting ideas came to light.

   Gettext is a great tool, however it introduces dependencies on shared
   objects (or requires static linking). Simply parsing command line
   arguments should not introduce additional dependencies. Additionally,
   standard libc should not favor one internationalization library over
   another, therefore its just not practical to include
   internationalization in standard libc. However, stuff in libc that
   prints strings can remain friendly to internationalization by simply
   requiring one tiny additional step - have the programmer register a
   callback function that gets all output instead of printing to the error
   file descriptor directly in libc.

   For instance, a modern getopt might look like this:

   void getopt_callback(int level, char *format, int line)
   {
    switch (level) {
    case GETOPT_EOK:
     fprintf(stdout, "line %d of getopt.c says %s", line, format);
     break;
    case GETOPT_EFAIL:
     fprintf(stderr, "line %d of getopt.c says %s", line, format);
     break;
    }
    return;
   }
   int main(int argc, char **argv)
   {
    int c, opt_ind;
    getopt_register_callback(getopt_callback);
    for (c = 0, optind = 0, opt_ind = 0; c != -1;) {
     c = getopt_long(argc, argv, "f:o:O", long_options, &opt_ind);
     ......

   As we can see, the getopt implementation does not actually print
   anything, it allows the callback function to handle that. One could
   very easily use internationalization tools within the callback, if they
   wanted to do so. This goes (basically) for anything in core libc that
   prints anything. The callback may be better typed as something like
   getopt_callback_t.

   This seems to be the favorable approach. Of course, getopt would
   feature its own static callback that printed the strings as-is if the
   calling function did not register one, this keeps from breaking
   existing use.

   After I finish some other tasks, I am going to take a stroll through
   the HelenOS userspace generic libc to see if getopt is the only case
   where this should be implemented. At the least, I'll implement this
   getopt method there so that programs can be fully internationalized.

   This also shows the virtue of not using printf() directly when you can
   avoid it. Writing your own functions to print warnings or messages
   allows someone else (even you) to go back and make only a few minor
   changes in order for your program to support any language.

   Working on a new OS that aims to be fully modern presents interesting
   opportunities to pick things apart. Hopefully, this didn't put you to
   sleep :)
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You might also enjoy reading:

     * [29]For Concurrency Issues, There Is Music (0)
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     * [31]Xen And Single System Images (0)

   Tags: [32]helenos, [33]Ideas, [34]interesting, [35]Programming

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  40. http://echoreply.us/tech/2009/02/19/yes-im-still-alive/
  41. http://echoreply.us/tech/2009/01/05/please-adopt-etcvendor/
  42. http://echoreply.us/tech/2008/12/30/my-list-for-2009/
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  69. http://stackoverflow.com/
  70. http://echoreply.us/tech/2009/03/
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