R devel - Jun 2023 - restoring LANGUAGE env variable within an R session

I was playing around with the setting of the LANGUAGE variable and am 
wondering whether I'm missing something obvious about resetting the 
value to its original state once it's been set.  I seem to be able to 
reset the language for warnings/errors once, but not to change it a 
second time (or reset it) once it's been set ... ??

## default (no LANGUAGE set, English locale)
 > sqrt(-1)
[1] NaN
Warning message:
In sqrt(-1) : NaNs produced
## no complaints, doesn't change (as expected)
 > Sys.setenv(LANGUAGE = "en")
 > sqrt(-1)
[1] NaN
Warning message:
In sqrt(-1) : NaNs produced

## change to German
 > Sys.setenv(LANGUAGE = "de")
 > sqrt(-1)
[1] NaN
Warnmeldung:
In sqrt(-1) : NaNs wurden erzeugt

## try to change to Spanish - no luck
## (this does work in a clean session)

 > Sys.setenv(LANGUAGE = "es")
 > sqrt(-1)
[1] NaN
Warnmeldung:
In sqrt(-1) : NaNs wurden erzeugt

## try resetting to blank
 > Sys.setenv(LANGUAGE = "")
 > sqrt(-1)
[1] NaN
Warnmeldung:
In sqrt(-1) : NaNs wurden erzeugt

## or back to English explicitly?
 > Sys.setenv(LANGUAGE = "en")
 > sqrt(-1)
[1] NaN
Warnmeldung:
In sqrt(-1) : NaNs wurden erzeugt
 >

Ben,

POSIX level / glibc level variables are set at process start and AGAIK cannot
really be altered after start.  They clearly work when set _before_ calling
sqrt(-1):

    $ LANGUAGE=es Rscript -e 'sqrt(-1)'
    [1] NaN
    Warning message:
    In sqrt(-1) : Se han producido NaNs
    $ LANGUAGE=de Rscript -e 'sqrt(-1)'
    [1] NaN
    Warnmeldung:
    In sqrt(-1) : NaNs wurden erzeugt
    $ 

I think the `callr` package can help you with this use from with R by
effectively spawning a new process for you. Or, lower-level, you can call
`system()` or `system2()` yourself and take care of the setup.

Cheers, Dirk

-- 
dirk.eddelbuettel.com | @eddelbuettel | edd at debian.org

Translated strings are cached.
I'd recommend to use the

     ? New partly experimental Sys.setLanguage() utility, solving the
       main problem of PR#18055.

introduced in R 4.2.0.

Best,

	Sebastian Meyer


Am 26.06.23 um 15:15 schrieb Ben Bolker:
>     I was playing around with the setting of the LANGUAGE variable and am
> wondering whether I'm missing something obvious about resetting the
> value to its original state once it's been set.  I seem to be able to
> reset the language for warnings/errors once, but not to change it a
> second time (or reset it) once it's been set ... ??
> 
> ## default (no LANGUAGE set, English locale)
>   > sqrt(-1)
> [1] NaN
> Warning message:
> In sqrt(-1) : NaNs produced
> ## no complaints, doesn't change (as expected)
>   > Sys.setenv(LANGUAGE = "en")
>   > sqrt(-1)
> [1] NaN
> Warning message:
> In sqrt(-1) : NaNs produced
> 
> ## change to German
>   > Sys.setenv(LANGUAGE = "de")
>   > sqrt(-1)
> [1] NaN
> Warnmeldung:
> In sqrt(-1) : NaNs wurden erzeugt
> 
> ## try to change to Spanish - no luck
> ## (this does work in a clean session)
> 
>   > Sys.setenv(LANGUAGE = "es")
>   > sqrt(-1)
> [1] NaN
> Warnmeldung:
> In sqrt(-1) : NaNs wurden erzeugt
> 
> ## try resetting to blank
>   > Sys.setenv(LANGUAGE = "")
>   > sqrt(-1)
> [1] NaN
> Warnmeldung:
> In sqrt(-1) : NaNs wurden erzeugt
> 
> ## or back to English explicitly?
>   > Sys.setenv(LANGUAGE = "en")
>   > sqrt(-1)
> [1] NaN
> Warnmeldung:
> In sqrt(-1) : NaNs wurden erzeugt
>   >
> 
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