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Re: How to add the second (or other) languages

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On 16/02/2025 23:15, pozz wrote:
> Il 12/02/2025 18:14, Stefan Reuther ha scritto:
>> Am 12.02.2025 um 17:26 schrieb pozz:
>>> #if LANGUAGE_ITALIAN
>>> #  define STRING123            "Evento %d: accensione"
>>> #elif LANGUAGE_ENGLISH
>>> #  define STRING123            "Event %d: power up"
>>> #endif
>> [...]
>>> Another approach is giving the user the possibility to change the
>>> language at runtime, maybe with an option on the display. In some cases,
>>> I have enough memory to store all the strings in all languages.
>>
>> Put the strings into a structure.
>>
>>    struct Strings {
>>        const char* power_up_message;
>>    };
>>
>> I hate global variables, so I pass a pointer to the structure to every
>> function that needs it (but of course you can also make a global 
>> variable).
>>
>> Then, on language change, just point your structure pointer elsewhere,
>> or load the strings from secondary storage.
>>
>> One disadvantage is that this loses you the compiler warnings for
>> mismatching printf specifiers.
>>
>>> I know there are many possible solutions, but I'd like to know some
>>> suggestions from you. For example, it could be nice if there was some
>>> tool that automatically extracts all the strings used in the source code
>>> and helps managing more languages.
>>
>> There's packages like gettext. You tag your strings as
>> 'printf(_("Event %d"), e)', and the 'xgettext' command will extract them
>> all into a .po file. Other tools help you manage these files (e.g.
>> 'msgmerge'; Emacs 'po-mode'), and gcc knows how to do proper printf
>> warnings.
>>
>> The .po file is a mapping from English to Whateverish strings. So you
>> would convert that into some space-efficient resource file, and
>> implement the '_' macro/function to perform the mapping. The
>> disadvantage is that this takes lot of memory because your app needs to
>> have both the English and the translated strings in memory. But unless
>> you also use a fancy preprocessor that translates your code to
>> 'printf(getstring(STR123), e)', I don't see how to avoid that. In C++20,
>> you might come up with some compile-time hashing...
>>
>> I wouldn't use that on a microcontroller, but it's nice for desktop apps.
> 
> In some projects keeping all the translated strings is not a problem.
> 
> All the gettext tools seem good (xgettext, marking strings to translate 
> in the source code, pot file, msginit, msgmerge, msgfmt, po files, mo 
> files, ..) except the final step.
> 
> mo files should be installed in a file-system and gettext library 
> automatically loads the correct .mo file from a suitable path. All these 
> things are impractical on microcontroller systems.
> 
> Is it so difficult to import mo files as C const unsigned char arrays 
> and implement the gettext() function to search strings from them?
> 

You know the answer...  a little Python script that reads mo files and 
generates files with C constant arrays.  You'd also probably need to 
make a few changes to the gettext language choice functions.  (I've used 
gettext with big Python programs, but never in embedded C code.)

> Another approach could be to rewrite a custom msgfmt tool that converts 
> a .po file into a simpler .mo file (or directly a .c file) that can be 
> used by a custom gettext() function.

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Thread

How to add the second (or other) languages pozz <pozzugno@gmail.com> - 2025-02-12 17:26 +0100
  Re: How to add the second (or other) languages Stefan Reuther <stefan.news@arcor.de> - 2025-02-12 18:14 +0100
    Re: How to add the second (or other) languages David Brown <david.brown@hesbynett.no> - 2025-02-12 20:50 +0100
      Re: How to add the second (or other) languages pozz <pozzugno@gmail.com> - 2025-02-16 19:59 +0100
        Re: How to add the second (or other) languages David Brown <david.brown@hesbynett.no> - 2025-02-17 09:51 +0100
          Re: How to add the second (or other) languages pozz <pozzugno@gmail.com> - 2025-02-17 16:05 +0100
            Re: How to add the second (or other) languages David Brown <david.brown@hesbynett.no> - 2025-02-17 19:09 +0100
      Re: How to add the second (or other) languages pozz <pozzugno@gmail.com> - 2025-02-16 22:56 +0100
        Re: How to add the second (or other) languages David Brown <david.brown@hesbynett.no> - 2025-02-17 09:57 +0100
    Re: How to add the second (or other) languages pozz <pozzugno@gmail.com> - 2025-02-16 23:15 +0100
      Re: How to add the second (or other) languages David Brown <david.brown@hesbynett.no> - 2025-02-17 09:59 +0100
      Re: How to add the second (or other) languages Stefan Reuther <stefan.news@arcor.de> - 2025-02-17 19:00 +0100
  Re: How to add the second (or other) languages "Niocláiſín Cóilín de Ġloſtéir" <Master_Fontaine_is_dishonest@Strand_in_London.Gov.UK> - 2025-02-13 22:51 +0100

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