From: Nobuyoshi Nakada <nobu@...>
Date: 2009-06-07T02:28:36+09:00
Subject: Re: Iconv and incompatible encodings

Hi,

At Sun, 7 Jun 2009 00:24:55 +0900,
Adam Strzelecki wrote in [ruby-talk:338586]:
> Thanks, your solution is really more Ruby-way. I just wonder why 
> "setlocale" isn't a part of Ruby standard library. Since Ruby maps/wraps 
> most of the standard (POSIX) functions (especially those available on 
> Windows too), this one should be also taken into consideration.

It affects library functions, such as printf(), and can cause
problems.

> > First of all, option after // is GNU iconv local extension.
> Sure I know that, but it doesn't mean it is EVIL, is it? Still it is 
> very useful for creating permalinks and removing accented characters 
> simply, w/o using any third party libraries and so, but unusable until 
> we call POSIX setlocale, which isn't present in Ruby API.

You can't rely on it if you want write portable script.

> > Second, extconf.rb must check for the necessary header, and
> > whether each categories are defined.
> 
> Still it should be present on every system (AFAIK it is), since quoting 
> man: "The setlocale() function conforms to ISO/IEC 9899:1999 (``ISO 
> C99'').". Is there anyone who checks whether <stdio.h> exists?

Not all systems conform to C99, and not all categories are
available on all systems.  For instance, mingw and perhaps
mswin don't have LC_MESSAGES.

> > And it feels too redundant.  I guess Locale.ctype = '' would be easy.
> 
> Sure yours is better. Mine didn't consider fact that some of constants 
> may have different values on different systems.

Of course, otherwise why they need the macros?

> If it is was to be included into standard library I'd leave 
> Locale::setlocale method as well, as you may combine types there and 
> also check returned value, where nil means failed association and String 
> on successful one, where documentation doesn't explicitly say that 
> returned string is exactly the one that was passed. So with simple 
> Locale::ctype= we may miss some important feedback.

You mean setters should raise an exception on error?


#include <locale.h>
#include "ruby.h"

static VALUE
rb_setlocale(int category, const char *locale)
{
    char *r = setlocale(category, locale);
    if (!r) rb_raise(rb_eRuntimeError, "setlocale");
    return rb_str_new2(r);
}

static inline VALUE
locale_set(int category, VALUE locale)
{
    return rb_setlocale(category, StringValueCStr(locale));
}

static inline VALUE
locale_get(int category)
{
    return rb_setlocale(category, NULL);
}

#define funcs(n, c) \
static VALUE rb_getlocale_##n(VALUE self) {return locale_get(c);} \
static VALUE rb_setlocale_##n(VALUE self, VALUE val) {return locale_set(c, val);} \
/* end of funcs */

foreach_categories(funcs)

void
Init_locale(void)
{
    VALUE locale = rb_define_module("Locale");
#define methods(n, c) \
    rb_define_singleton_method(locale, #n, rb_getlocale_##n, 0); \
    rb_define_singleton_method(locale, #n"=", rb_setlocale_##n, 1); \
    /* end of methods */

    foreach_categories(methods);
}


-- 
Nobu Nakada