[Rd] Change in package.skeleton behavior from R 3.6.3 to R 4.0.0 ?

[Dirk Eddelbuettel]

The Rcpp package and some related packages such as RcppArmadillo make use of
(local) wrappers around the utils::package.skeleton() function for creating
(basic yet functional) packages using Rcpp or RcppArmadillo. RStudio also
exposes this under the graphical menu as a nice way to construct a package.

But it seems that something changed quite recently in R. I looked into this a
little yesterday and prepared a workaround for Rcpp; Kevin (CC'ed) was more
diligent and found what changed with R itself. See the discussion under issue
ticket #1087 at the Rcpp repo: https://github.com/RcppCore/Rcpp/issues/1087
The proposed simple PR is at https://github.com/RcppCore/Rcpp/pull/1088

As Kevin mentions in #1087, R itself may have changed, and he even dug up a
possible commit [1]. One can illustrate that quickly with two different R
interpreters, I use Docker here because that's what I often do. I apologise
for the long command-line; that is basically just common Docker arguments.
The keys are r-base:3.6.3 and r-base:4.0.0 for selecting the relevant R
builds, and the command string passed to bash to call Rscript and
package.skeleton() followed by a cat of the NAMESPACE file.

-----------------------------------------------------------------------------
edd using rob:/tmp$ mkdir skeleton
edd using rob:/tmp$ cd skeleton/
edd using rob:/tmp/skeleton$ docker run --rm -ti -u1000:1000 -v ${PWD}:/mnt -w /mnt r-base:3.6.3 bash -c "Rscript -e 'x <-1L; package.skeleton(name=\"p363\")'; cat p363/NAMESPACE"
Creating directories ...
Creating DESCRIPTION ...
Creating NAMESPACE ...
Creating Read-and-delete-me ...
Saving functions and data ...
Making help files ...
Done.
Further steps are described in './p363/Read-and-delete-me'.
exportPattern("^[[:alpha:]]+")
edd using rob:/tmp/skeleton$ docker run --rm -ti -u1000:1000 -v ${PWD}:/mnt -w /mnt r-base:4.0.0 bash -c "Rscript -e 'x <-1L; package.skeleton(name=\"p400\")'; cat p400/NAMESPACE"
Creating directories ...
Creating DESCRIPTION ...
Creating NAMESPACE ...
Creating Read-and-delete-me ...
Saving functions and data ...
Making help files ...
Done.
Further steps are described in './p400/Read-and-delete-me'.
export("x")
edd using rob:/tmp/skeleton$ 
-----------------------------------------------------------------------------

In short, 4.0.0 no longer exports via 'exportPattern("^[[:alpha:]]+")'
rendering the new package created non-functional. 

Was this intentional, or is this a bug we can look into fixing for R 4.0.2 ?

Dirk


[1] This uses the GitHub mirror rather than svn but the underlying code is of
course the same
https://github.com/wch/r-source/commit/36b27d951fb355f268191a25909ab292a273932d#diff-a1b94fcea8b8818d4371aabf04dc2b3c 

-- 
http://dirk.eddelbuettel.com | @eddelbuettel | edd using debian.org