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

[Duncan Murdoch]

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