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?
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
