Setlocale and wchar_t C functions...

[Umberto Nicoletti]

On 6/22/07, Steve Lime <Steve.Lime at dnr.state.mn.us> wrote:
> Hi all: I'm working to resolve bug 1921 with deals with curved labels and multibyte character sets. The current label path
> code doesn't handle multibyte character sets. Fortunately standard C (on Linux and MacOS anyway) have some functions
> to deal with the problem. For example mbstowcs converts from a multibyte string to a wide character string. The behavior
> of those functions depend on the locale. Unless you are in a local with multibyte characters those functions don't work
> with multibyte chars and assume single byte chars. Found that out trying to draw Chinese characters with the default US-EN
> locale. If I set the local to one with multibyte characters then I could debug.
>
> A couple of questions then:
>
>   - what would folks think about adding a LOCALE parameter to the main mapObj? We could to a setlocale(LC_ALL, msyytext)
> immediately. If not set, then whatever the system has set takes over.
>
>   - as I understand it setlocale has a global effect so perhaps there might be some down stream side effects, although I can't
> think what they might be. I suppose for long running processes there could be issues. I can see where a company might want
> to provide maps in different languages from the same server.

Steve,
calling setlocale from mapserver will also change the locale of the
mapscript language which means, for Java, a global change of the
locale behaviour in the application server which is, I believe, not a
really good idea. The same happens with python, c#, etc and PHP
mapscript loaded as shared module will change the locale of apache.
I also seem to remember that calls to setlocale are not thread safe.

A similar question was raised some time ago and at that time it was
somehow decided not to call setlocale from within mapserver.
See the thread titled: 'Proposing to call setlocale( LC_ALL, "C" ) in msSetup()'

To set the locale for a process one should use the usual environment
variables (LANG or LC_ALL). In particular it is possible to do this on
a per-map basis for the CGI version of mapserver either from whithin
apache or with a wrapper shell script.

Regards,
Umberto


>
>   - are the wide character functions (stdlib.h) available on all platforms?
>
> Steve
>