[R-pkg-devel] Wrong mailing list: Could the 100 byte path length limit be lifted?

[Henrik Bengtsson]

On Wed, Dec 13, 2023 at 8:06 AM McGrath, Justin M <jmcgrath using illinois.edu> wrote:
>
> On Windows, packages will be in "C:\Users\[User Name]\Documents\R\win-library\[R version]\[Package Name]".

In R (>= 4.2.0), the default R_LIBS_USER path has moved to under
LOCALAPPDATA, e.g. "C:\Users\[User
Name]\AppData\Local\R\win-library\[R version]".  See
https://cran.r-project.org/bin/windows/base/rw-FAQ.html

FWIW, one workaround for too long paths on MS Windows is to map a long
path to a drive letter, e.g.

subst Y: 'C:/VeryLongPathToo/Users/JohnDoe/AppData/Local/R/'.

and then work with Y: instead of C:. We had to use that in some
projects with nested data folder structures. This approach is tedious,
and might require special permissions (not sure).

/Henrik

>
> With a 150 byte limit, that leaves 70 bytes for the user name, R version and package name. That seems more than sufficient. If people are downloading the source files, that also leaves plenty of space regardless where they choose to extract the files.
>
> ________________________________________
> From: Dirk Eddelbuettel <edd using debian.org>
> Sent: Wednesday, December 13, 2023 9:13 AM
> To: Tomas Kalibera
> Cc: Dirk Eddelbuettel; McGrath, Justin M; Ben Bolker; Martin Maechler; r-package-devel using r-project.org
> Subject: Re: [R-pkg-devel] Wrong mailing list: Could the 100 byte path length limit be lifted?
>
>
> On 13 December 2023 at 16:02, Tomas Kalibera wrote:
> |
> | On 12/13/23 15:59, Dirk Eddelbuettel wrote:
> | > On 13 December 2023 at 15:32, Tomas Kalibera wrote:
> | > | Please don't forget about what has been correctly mentioned on this
> | > | thread already: there is essentially a 260 character limit on Windows
> | > | (see
> | > | https://urldefense.com/v3/__https://blog.r-project.org/2023/03/07/path-length-limit-on-windows/index.html__;!!DZ3fjg!-NHAlEZQvY2kegkNVkuY3Lf84nKmMahrpZ4Euz2XXFDPvMWEcP28iepLlRiKzVZdAh752lyhHxd6zvk$
> | > | for more). Even if the relative path length limit for a CRAN package was
> | > | no longer regarded important for tar compatibility, it would still make
> | > | sense for compatibility with Windows. It may still be a good service to
> | > | your users if you keep renaming the files to fit into that limit.
> | >
> | > So can lift the limit from 100 char to 260 char ?
> |
> | The 260 char limit is for the full path. A package would be extracted in
> | some directory, possibly also with a rather long name.
>
> Call a cutoff number.
>
> Any move from '100' to '100 + N' for any nonzero N is a win. Pick one, and
> then commit the change.  N = 50 would be a great start as arbitrary as it is.
>
> Dirk
>
> --
> dirk.eddelbuettel.com | @eddelbuettel | edd using debian.org
>
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