[R-pkg-devel] Rcpp: how best to include source from another Github repository

[Dirk Eddelbuettel]

On 21 January 2025 at 12:04, Jonathan Berrisch wrote:
| first of all: I'm not an expert on this and don't really know if there 
| is a recommended way.
| 
| However, you may look at my 'rcpptimer' package and how it includes 
| 'cpptimer' as a submodule.
| 
| You can find the repository here: https://github.com/BerriJ/rcpptimer

I had written a longer (private) email to John expressing the view that git
submodules "were once more 'en vogue'" but one sees them less these days.
One reason is that they break some (somewhat standard) workflows, see below.

Overall, this is "no win" situation. You can include the files in the package
as a copy [2] enlarging the package, build process, etc but arguably making
it more robust, or you can keep it external which is cleaner -- but harder as
you now have to ensure users (and CRAN !) can get / have that library.

So it is all tradeoffs one has to make.

Dirk


[1] Log from a standard r2u Ubuntu container, `git` and `ssh` added as needed:

root using 4163d5544547:/# installGithub.r https://github.com/BerriJ/rcpptimer
Downloading GitHub repo BerriJ/rcpptimer using HEAD
'/usr/bin/git' clone --depth 1 --no-hardlinks --recurse-submodules git using github.com:BerriJ/cpptimer.git /tmp/remotes257564d64e0/BerriJ-rcpptimer-35ca024/inst/include/cpptimer
Cloning into '/tmp/remotes257564d64e0/BerriJ-rcpptimer-35ca024/inst/include/cpptimer'...
The authenticity of host 'github.com (140.82.113.3)' can't be established.
ED25519 key fingerprint is SHA256:+DiY3wvvV6TuJJhbpZisF/zLDA0zPMSvHdkr4UvCOqU.
This key is not known by any other names.
Are you sure you want to continue connecting (yes/no/[fingerprint])? yes
Warning: Permanently added 'github.com' (ED25519) to the list of known hosts.
git using github.com: Permission denied (publickey).
fatal: Could not read from remote repository.

Please make sure you have the correct access rights
and the repository exists.
Error: Failed to install 'rcpptimer' from GitHub:
  Command failed (128)
In addition: Warning message:
In system(full, intern = TRUE, ignore.stderr = quiet) :
  running command ''/usr/bin/git' clone --depth 1 --no-hardlinks --recurse-submodules git using github.com:BerriJ/cpptimer.git /tmp/remotes257564d64e0/BerriJ-rcpptimer-35ca024/inst/include/cpptimer' had status 128 and error message 'Function not implemented'
root using 4163d5544547:/# 
exit


[2] The "Rcpp-library" vignette John refers to also mentions (IIRC) that this
is preferable for smaller libraries; its 'corels' example fits that
description.  These days other authors also vendor entire applications such
as whole SQL engines: ¯\_(ツ)_/¯  I just updated qlcal on CRAN, it explicitly
copies the calendaring (subset) from QuantLib as I learned over 20 years that
users have difficulties with that large library. Tradeoffs.

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