[R-pkg-team] Bug in r-base and r-cran-rcppparallel

[Dirk Eddelbuettel]

On 11 February 2021 at 12:50, Johannes Ranke wrote:
| Am Donnerstag, 11. Februar 2021, 12:20:33 CET schrieb Bastian Blank:
| > Hi Johannes
| 
| Hello Bastian!
| 
| > On Thu, Feb 11, 2021 at 09:26:48AM +0100, Johannes Ranke wrote:
| > > dyn.load is used in base R to load compiled code from R packages.
| > 
| > Can you show some examples please?  I know C and POSIX, but not much
| > about R.
| 
| Well, in a nutshell, loading a package in R means calling library [1] which in 
| turn calls loadNamespace [2] which, if the package uses compiled code, calls 
| library.dynam [3], which uses dyn.load [4] after normalizing the path to the 
| DLL.
| 
| So if you load e.g. the package MASS in R, dyn.load is called:
| 
| R> debug(dyn.load) 
| R> library(MASS) 
| debugging in: dyn.load(file, DLLpath = DLLpath, ...) 
| debug: .Internal(dyn.load(x, as.logical(local), as.logical(now), "")) 
| Browse[2]> x 
| [1] "/usr/local/lib/R/site-library/MASS/libs/MASS.so" 
| 
| ...
| 
| > > The documentation of dyn.load says that it accepts a path to a dynamic
| > > shared object. Do we need more than that?
| > 
| > So my change is no problem, because it only changes the behaviour for
| > 'dyn.load("object.so")', but not for
| > 'dyn.load("/home/foo/projects/bar/object.so")'.
| > 
| > The documentation does not list a search behaviour for bare library
| > names on non-Windows systems.  So completely ignoring the system library
| > paths is kind of weird.
| 
| I can see that it looks weird - but is it a bug?

Exactly. It has been like that since the 1990s when R's packaging system was
set up. We have hundreds of per package shared libraries. Even the first one
I packaged for Debian (r-cran-rodbc, in 2003 if memory serves) used that.

"A feature not a bug" :)

Dirk
 
| Johannes
| 
| [1] https://github.com/wch/r-source/blob/trunk/src/library/base/R/
| library.R#L54 
| 
| [2] https://github.com/wch/r-source/blob/trunk/src/library/base/R/
| namespace.R#L185 
| 
| [3] https://github.com/wch/r-source/blob/trunk/src/library/base/R/
| library.R#L572 

-- 
https://dirk.eddelbuettel.com | @eddelbuettel | edd at debian.org