Re: Accessing the environment's locale encoding settings

[Bruno Haible]

Ludovic Courtès wrote:
> It seems to me that the implicit call is often desirable, but at the
> same time, it imposes a policy on the application.  In C, Guile, & co.,
> the application can choose to ignore the locale, or to just honor
> LC_CTYPE, or to set something different.

What it actually does, then, is that it uses a mix of the user-provided
locale (for some locale categories) and the "C" locale (for some other
locale categories. When the default category is the user-provided one,
rather than "C", it is still possible, it just needs different code to
do so.

Instead of
    (setlocale LC_CTYPE "")
the user will now need to write
    (setlocale LC_NUMERIC "C")
    (setlocale LC_MONETARY "C")
    (setlocale LC_COLLATE "C")
    (setlocale LC_MESSAGES "C")
    (setlocale LC_TIME "C")

> > So my suggestion is to do (setlocale LC_ALL "") as part of the Guile
> > initialization, very early. Yes, this might lead to some complexity
> > in the Guile implementation if you have the concept of locale also at
> > the Guile level and need to make sure that the locale at the C level and
> > the locale at the Guile level are consistent as soon as the latter is
> > defined. But this is manageable.
> 
> Are you suggesting that we could arrange to have Guile’s ‘main’ call
> setlocale(LC_ALL, "") while still giving Scheme code the impression that
> it’s started under the C locale as is currently the case?

No, I'm suggesting to let the Scheme code know that is it using the user's
locale.

Yes, this is a backward-incompatible change, so probably you won't want to
do it on the guile 2.0.x branch, and you will want to advertise it in the
release notes or NEWS file.

> A reasonable option would be to setlocale(LC_CTYPE, "") from Guile’s
> ‘main’, so that scm_from_locale_string & co. would DTRT.  But again that
> would change the value of %default-port-encoding, leading to potential
> application breakage.

In the long run, this would be more complex: users who see that LC_CTYPE
from the environment is respected would also expect that LC_COLLATE etc.
from the environment is respected.

I would just do the change and make it clear that old applications that
really want to stay in the C locale should call
  (setlocale LC_ALL "C")

Bruno
-- 
In memoriam Kerem Yılmazer <http://en.wikipedia.org/wiki/Kerem_Yılmazer>