I sent this enquiry to r-help and received several sympathetic replies, none of which were definitive. It was kindly suggested to me that I might get better mileage out of r-devel, so I'm trying here. I hope that this is not inappropriate. My original enquiry to r-help: =========================================================================I am working with a function "foo" that explicitly dynamically loads a shared object library or "DLL", doing something like dyn.load("bar.so"). This is a debugging exercise so I make changes to the underlying Fortran code (yes, I acknowledge that I am a dinosaur) remake the DLL "bar.so" and then run foo again. This is all *without* quitting and restarting R. (I'm going to have to do this a few brazillion times, and I want the iterations to be as quick as possible.) This seems to work --- i.e. foo seems to obtain the latest version of bar.so. But have I just been lucky so far? (I have not experimented heavily). Am I running risks of leading myself down the garden path? Are there Traps for Young (or even Old) Players lurking about? I would appreciate Wise Counsel. ========================================================================= One of the replies that I received from r-help indicated that it might be safer if I were to apply dyn.unload() on each iteration. So I thought I might put in the line of code on.exit(dyn.unload("bar.so")) immediately after my call to dyn.load(). Comments? Another reply pointed out that "Writing R Extensions" indicates that there could be problems under Solaris, but does not single out any other OS for comment. Might I infer that I am "safe" as long as I don't use Solaris? (Which I certainly *won't* be doing.) Thanks. cheers, Rolf Turner -- Technical Editor ANZJS Department of Statistics University of Auckland Phone: +64-9-373-7599 ext. 88276