How to unload a dll loaded via library.dynam()?

Hmmm, I think restarting R is not a very good solution. It is rather
ugly in the first place. But perhaps even more importantly, it can be
rather inconvenient if one has a large data set in the memory and
needs to save/load it just to reload a package that was updated in the
meanwhile.

This happens to me quite often with 20-40Gb of data, so I would really
love to have a solution for proper detach/unload.

Best,
Gabor

On Fri, Feb 20, 2009 at 1:32 AM, Duncan Murdoch <murdoch at stats.uwo.ca> wrote:

On 19/02/2009 6:19 PM, Alex F. Bokov wrote:

Hello. To save the hassle of quitting and restarting R every time I
rebuild the package I'm working on (for the purposes of this question called
"roots") I would like to write a script cleanly remove the package from my R
session and then load it again. Of course detach("package:roots") works for
the native R objects in the package. However, the compiled C library remains
loaded. Using library.dynam.unload as documented results in:

Error in library.dynam.unload("roots.so",
"~/R/x86_64-pc-linux-gnu-library/2.8/roots/libs/") :
 shared library 'roots' was not loaded

I also tried the above command with the file extension omitted and the
last one and two levels of the directory path omitted. In both cases I still
get the "not loaded" error. I've also Googled the list archives and while
there were several questions like mine, none of them were answered by the
list. Am I to believe that this is something hardly anybody does? Does this
mean everybody sits around waiting for R to start up everytime they make a
minor change to the C source?

If there is a tutorial for doing this, I'd much appreciate the link.

This is more of an R-devel question than R-help, so if this doesn't answer
your question, please follow up there.

On Windows, the following sort of works:

library(rgl)
.dynLibs()

                                          Filename Dynamic.Lookup
1     F:/R/R-2.8.1/library/methods/libs/methods.dll          FALSE
2 F:/R/R-2.8.1/library/grDevices/libs/grDevices.dll          FALSE
3         F:/R/R-2.8.1/library/stats/libs/stats.dll          FALSE
4             F:/R/R-2.8.1/library/rgl/libs/rgl.dll           TRUE

library.dynam.unload("rgl", "F:/R/R-2.8.1/library/rgl")

I say "sort of", in that I get no error messages and the dll is no longer
locked in use as it normally would be in Windows, but reloading the package
doesn't function properly. It's possible some combination of detach() and
unloadNamespace() would get a clean unload, but really, I normally just quit
R and restart.  It's pretty quick to start up, compared to the recompile
time for the package.

Duncan Murdoch

-- 
Gabor Csardi <Gabor.Csardi at unil.ch>     UNIL DGM