How do I support gettext to internationalize multilingualism?

[fengdaolong]

I want to use gettext for internationalization support, my code is as follows:

    std::string world = "World";
    SPDLOG_INFO(boost::locale::gettext("Hello {}"), world);

When I compile, the following error is reported. It seems that the first argument to the SPDLOG_INFO macro does not support strings computed at runtime. What should I do?

In file included from /tmp/develop/linux_agent/src/main.cpp:67:
/tmp/develop/linux_agent/src/main.cpp: In function ‘int main(int, const char**)’:
/tmp/develop/linux_agent/thirdparty/spdlog/include/spdlog/spdlog.h:288:22: error: call to non-‘constexpr’ function ‘std::__cxx11::basic_string<_CharT> boost::locale::gettext(const CharType*, const std::locale&) [with CharType = char]’
  288 |         (logger)->log(spdlog::source_loc{__FILE__, __LINE__, SPDLOG_FUNCTION}, level, __VA_ARGS__)
      |         ~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/tmp/develop/linux_agent/thirdparty/spdlog/include/spdlog/spdlog.h:314:9: note: in expansion of macro ‘SPDLOG_LOGGER_CALL’
  314 |         SPDLOG_LOGGER_CALL(logger, spdlog::level::info, __VA_ARGS__)
      |         ^~~~~~~~~~~~~~~~~~
/tmp/develop/linux_agent/thirdparty/spdlog/include/spdlog/spdlog.h:315:30: note: in expansion of macro ‘SPDLOG_LOGGER_INFO’
  315 |     #define SPDLOG_INFO(...) SPDLOG_LOGGER_INFO(spdlog::default_logger_raw(), __VA_ARGS__)
      |                              ^~~~~~~~~~~~~~~~~~
/tmp/develop/linux_agent/src/main.cpp:357:5: note: in expansion of macro ‘SPDLOG_INFO’
  357 |     SPDLOG_INFO(boost::locale::gettext("Hello {}"), world);
      |     ^~~~~~~~~~~
In file included from /usr/include/boost/locale/format.hpp:13,
                 from /usr/include/boost/locale.hpp:16,
                 from /tmp/develop/linux_agent/src/common/localization.hpp:4,
                 from /tmp/develop/linux_agent/src/main.cpp:65:
/usr/include/boost/locale/message.hpp:432:33: note: ‘std::__cxx11::basic_string<_CharT> boost::locale::gettext(const CharType*, const std::locale&) [with CharType = char]’ declared here
  432 |     std::basic_string<CharType> gettext(const CharType* id, const std::locale& loc = std::locale())
      |                                 ^~~~~~~

[gabime]

Try wrapping with SPDLOG_FMT_RUNTIME

[fengdaolong]

Use SPDLOG_FMT_RUNTIME wrapping can be used, thanks for guidance!

[fengdaolong]

Now I have a new problem:

I defined the following macro to simplify gettext string extraction. However, the _(str) macro can only wrap the Spdlog string, and a compilation error occurs when this macro wraps other strings in the project. What am I supposed to do?

#define _(str) SPDLOG_FMT_RUNTIME(boost::locale::gettext(str).c_str())

std::string world = "World";
SPDLOG_INFO(_("Hello {}"), world);

[tt4g]

I don't see why it should be wrapped using the SPDLOG_FMT_RUNTIME macro when it is not a string to be passed to spdlog.
Translation and logging have different purposes. Why try to accomplish different purposes with one macro?

[fengdaolong]

The reason for wrapping the string with the same macro is purely for the convenience of unification.
However, I don't know if there is any compatible way for the spdlog string.

[tt4g]

SPDLOG_FMT_RUNTIME does not return a string.
It returns a structure to identify that the format string is not determined until runtime.