Should the DESCRIPTION file have a Languages field?

[leofontenelle]

@rffontenelle was asked by a ROpenSci maintainer [^ROpenSci] why doesn't data.table have a Language field in the DESCRIPTION file. Quoting the Writing Extentions manual:

A ‘Language’ field can be used to indicate if the package documentation is not in English: this should be a comma-separated list of standard (not private use or grandfathered) IETF language tags as currently defined by RFC 5646 (https://www.rfc-editor.org/rfc/rfc5646, see also https://en.wikipedia.org/wiki/IETF_language_tag), i.e., use language subtags which in essence are 2-letter ISO 639-1 (https://en.wikipedia.org/wiki/ISO_639-1) or 3-letter ISO 639-3 (https://en.wikipedia.org/wiki/ISO_639-3) language codes.

Our guess was this is not an oversight. However, I couldn't find any discussion about this decision in the `NEWS files nor on the GitHub issues, open or otherwise. So, I opened this issue to discuss this (argh) issue, just in case.

[^ROpenSci]: Today there was a community call for pt_BR translation of ROpenSci and we both attended to share our experience with data.table.

[MichaelChirico]

Thanks for flagging. My understanding is when that key is used, the man/ pages (and/or possibly vignettes/) should be in that language, e.g.

https://github.com/cran/covidmx/blob/master/man/casos.Rd https://github.com/cran/SARP.moodle/blob/master/man/csv_glossaire.Rd

I also see cases clearly not adhering to this in man/ e.g.

https://github.com/cran/timeperiodsR/blob/master/man/weekends_length.Rd

However that package's vignettes are in ru:

https://github.com/cran/timeperiodsR/blob/master/vignettes/tpr_intro.Rmd

Of course, we have pending work to translate man pages & vignettes, depending on how exactly that's implemented, we might add such a key later.

Full CRAN search:

https://github.com/search?q=org%3Acran+path%3Adescription+%2F%5Elanguage%3A+%28%5B%5Eer%5D%7Ce%5B%5En%5D%7Cr%5B%5E%28%5D%29%2F&ref=opensearch&type=code

[llrs]

I asked for that because I think it will make it easier for newcomers to use data.table if they knew the error messages can be in their languages. Error messages are not help pages but they are documentation (imho).

[MichaelChirico]

aside: thanks for kick-starting the investigation into "valid Language entries". it's led to a new R CMD check entry:

https://github.com/r-devel/r-svn/commit/3560b606eb2b815c3fe0c8a5ba801cccde4c72ff

https://bugs.r-project.org/show_bug.cgi?id=18818