Re: [boost] Review Request: Boost.Locale

Subject: Re: [boost] Review Request: Boost.Locale
From: Artyom (artyomtnk_at_[hidden])
Date: 2010-05-24 02:10:42

> One thing in particular that I was interested in is(are)
> codecvt
> facets.  
> I didn't any thing on this.  Why is
> that? 

Take a look on http://www.cplusplus.com/reference/std/locale/codecvt/

They allow you to imbue special charset to fstream and automatically
translate wide characters to normal encoding like UTF-8 or ISO-8859-8.


> Is this a separate
> subject or is that you believe they're not useful. 

Theoretically they are very useful.

For example:

    std::wofstream fs;
    fs.imbue(std::locale("he_IL.UTF-8"));
    fs.open("file.txt");
    fs << L"שלום"!

Would print UTF-8 output.

But...

- Many compilers/standard libraries do not implement locales at all.
  (GCC under Windows and Solaris, STL Port library)
- Support of locales and encoding is strictly limited to OS
  configuration. So on some host the above example would work on other
  it would throw invalid locale error.
- Some compilers/OSes do not support UTF-8 encodings (MSVC) so
  you can't create UTF-8 locale at all.
- Locales name are platform depended. For example under Windows
  you need Hebrew_Israel.1255 locale and under Linux he_IL.ISO-8859-8
  (and BTW 1255!=iso-8859-8)

So Boost.Locale reimplements standard codecvt facet to make this work
on any platform.

However there is still a limitation when working with 2 byte
characters (ie char16_t or wchar_t under windows) as Boost.Locale
would work correctly only with UCS-2

But this is actually C++ standard's limitation.

Best,
  Artyom