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Re: Multi-language support on embedded plarforms

Cross-posted to 2 groups.

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On 9/5/17 3:30 AM, pozz wrote:
> [This message is posted to comp.arch.embedded and comp.lang.c]
> 
> Just for reference, an embedded platform based on a MCU with integrated 
> Flash, for example a Cortex-Mx device.
> Here I consider only western languages (left-to-right and european 
> chars, english, french, german, spanish and so on).
> 
> The main problem is the translation of strings, maybe 10-100 strings.
> 
> I know something about gettext package that can't be used in those 
> embeded platforms. However I like the approach of gettext.
> 
>    print_to_display(x, y, "Hello world!");
> 
> is simply changed in:
> 
>    #include <gettext.h>
>    ...
>    print_to_display(x, y, _("Hello world!"));
> 
> In this way, the code stays highly readble as before introducing the 
> multi-language support. If a member of a structure needs a string, it is 
> a char * as usual.
> 
> The solution I found in embedded platforms is to use an array of array 
> of strings: one index for the string and one index for the language.
> 
>    enum lang_t { ENGLISH, ITALIAN, LANG_N };
>    enum string_t { STR_HELLO_WORLD, STR_HOW_ARE_YOU };
> 
>    const char *strings[STRING_N][LANG_N] = {
>      {  // STR_HELLO_WORLD
>        { "Hello world!", "Ciao mondo" }
>      },
>      {  // STR_HOW_ARE_YOU
>        { "How are you?", "Come stai?" }
>      },
>    };
> 
>    static enum lang_t lang = ENGLISH;
> 
>    const char *_(int string_idx) {
>      return strings[string_idx][lang];
>    }
> 
>    void set_language(enum lang_t new_language) {
>      lang = new_language;
>    }
> 
> 
> I don't like too much this approach for two reasons.
> The first, the line:
> 
>    print_to_display(x, y, _(STR_HELLO_WORLD));
> 
> is much less readable than
> 
>    print_to_display(x, y, _("Hello world!"));
> 
> 
> The second, I need to change the type of some members/variables from 
> char * to int:
> 
>    struct mystruct {
>      int title;  // Instead of char *title
>      ...
>    };
> 
> 
> Another approach I'm thinking is to embed all the translations in the 
> string, using a separator character that can't be used in normal strings.
> 
>    print_to_display(x, y, _("Hello world!|Ciao Mondo!"));
> 
> The _() function will search the translated string based on the current 
> language. If he can't find, it could return the first translation 
> (english).
> 
> This approach has some disadvantages. It's difficult to exclude one 
> language from the build. If the languages are more than a couple, the 
> strings will be very long. The order of the translations (first english, 
> than italian, ...) is important and you have to remember it for every 
> string.
> 
> 
> What approach do you use?

If you really want to look by string, then your _ function just needs to 
search the translation table for that value, and then return the string 
desired translation instead of passing in the index. The lookup will 
take a bit of time, but not that long given your number of strings, and 
if you sort the strings by the base translation, you could binary search 
to find it.

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Multi-language support on embedded plarforms pozz <pozzugno@gmail.com> - 2017-09-05 09:30 +0200
  Re: Multi-language support on embedded plarforms David Brown <david.brown@hesbynett.no> - 2017-09-05 10:43 +0200
    Re: Multi-language support on embedded plarforms Robert Wessel <robertwessel2@yahoo.com> - 2017-09-05 09:56 -0500
      Re: Multi-language support on embedded plarforms Ian Collins <ian-news@hotmail.com> - 2017-09-06 07:50 +1200
        Re: Multi-language support on embedded plarforms Robert Wessel <robertwessel2@yahoo.com> - 2017-09-05 17:11 -0500
          Re: Multi-language support on embedded plarforms Keith Thompson <kst-u@mib.org> - 2017-09-05 15:17 -0700
            Re: Multi-language support on embedded plarforms Robert Wessel <robertwessel2@yahoo.com> - 2017-09-05 19:19 -0500
              Re: Multi-language support on embedded plarforms raltbos@xs4all.nl (Richard Bos) - 2017-09-09 12:37 +0000
                Re: Multi-language support on embedded plarforms Robert Wessel <robertwessel2@yahoo.com> - 2017-09-09 16:16 -0500
                Re: Multi-language support on embedded plarforms raltbos@xs4all.nl (Richard Bos) - 2017-09-15 17:17 +0000
          Re: Multi-language support on embedded plarforms Allan Herriman <allanherriman@hotmail.com> - 2017-09-06 11:27 +0000
  Re: Multi-language support on embedded plarforms Paul <paul@pcserviceselectronics.co.uk> - 2017-09-05 10:04 +0100
    Re: Multi-language support on embedded plarforms Theo Markettos <theom+news@chiark.greenend.org.uk> - 2017-09-06 10:55 +0100
  Re: Multi-language support on embedded plarforms Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2017-09-05 17:00 -0400
  Re: Multi-language support on embedded plarforms Keith Thompson <kst-u@mib.org> - 2017-09-07 10:55 -0700
    Re: Multi-language support on embedded plarforms scott@slp53.sl.home (Scott Lurndal) - 2017-09-07 18:41 +0000
    Re: Multi-language support on embedded plarforms pozz <pozzugno@gmail.com> - 2017-09-08 11:33 +0200
      Re: Multi-language support on embedded plarforms bartc <bc@freeuk.com> - 2017-09-08 11:32 +0100
        Re: Multi-language support on embedded plarforms David Brown <david.brown@hesbynett.no> - 2017-09-08 13:37 +0200
          Re: Multi-language support on embedded plarforms bartc <bc@freeuk.com> - 2017-09-08 14:48 +0100
            Re: Multi-language support on embedded plarforms David Brown <david.brown@hesbynett.no> - 2017-09-08 16:45 +0200
  Re: Multi-language support on embedded plarforms Richard Damon <Richard@Damon-Family.org> - 2017-09-08 10:43 -0400
    Re: Multi-language support on embedded plarforms Mel Wilson <mwilson@the-wire.com> - 2017-09-08 17:33 +0000

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