Re: UTF-8 messages in exceptions ?

From:
Goran <goran.pusic@gmail.com>
Newsgroups:
comp.lang.c++.moderated
Date:
Mon, 19 Jul 2010 05:59:22 CST
Message-ID:
<d870fd74-56a2-45ed-a94e-a1d45c555151@k39g2000yqd.googlegroups.com>
On Jul 18, 12:28 am, Timothy Madden <terminato...@gmail.com> wrote:

Hello

I need to write some wrapper classes around a library that my client has,
and the error messages (and all the other strings in the library) are in
UTF-8. Can I somehow create an exception class derived from std::exception
(std::runtime_error) that could carry such messages ?

I mean the message returned std::exception::what() is assumed to be in the
application locale, and I can not just set the application locale to UTF-8.


If standard library and other librarries you use aren't localized,
then they are most likely in English, and that's OK for plain UTF-8.
So when you output what() to something UTF-8 aware, it's OK.

If they are localized, and are using specific locale (not UTF-8),
whoops! How about some simple mix-in derivation, e.g.:

class utf8_error
{
   virtual const char* what_utf8() const = 0;
}

then,

class my_error : public runtime_error, public utf8_error
{
   // Implement what and what_utf8
};

and finally, in you catch handlers, use:

string utf8_ed_what(const exception& e)
{
   const utf8_error* utf8 = dynamic_cast<const utf8_error*>(&e);
   if (utf8)
     return utf8->what_utf8();
   else
     return locale_text_to_utf8(e.what());
}

BTW, application locale is assumed? How? (Honest question).

Goran.

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