G'day all, On Fri, 20 Feb 2009 04:01:07 +0000 (GMT) Prof Brian Ripley <rip...@stats.ox.ac.uk> wrote:
> library.dynam.unload() does work if the OS is cooperative. And if > you have your package set up correctly and unload the namespace (and > not just detach the package if there is a namespace) then the shared > object/DLL will be unloaded. [...] I guess I have a similar code-install-test development cycle as Alex; and I seem to work on a cooperative OS (Kubuntu 8.04). My set up is that I install packages on which I work into a separate library. To test changes to such packages, I start R in a directory which contains a .Rprofile file which, via .libPaths(), adds the above library to the library path. In this R session I then test the changes. I also used to quit and restart R whenever I re-installed a package with namespace to test the changes made. Somehow I got the impression that this was the way to proceed when namespaces were introduced; and I did not realise until recently that better ways (unloading the namespace) exist. However, I noticed the following behaviour under R 2.8.1 and "R version 2.9.0 Under development (unstable) (2009-02-19 r47958)" which I found surprising: 1) In the running R session, issue the command "unloadNamespace(XXX)" 2) Do changes to the code of the package; e.g. add a "print("hello world")" statement to one of the R functions. 3) Install the new package 4) In the running R session, issue the command "library(XXX)" and call the R function that was changed. Result: "Hello world" is not printed, somehow the old R function is still used. If I issue the commands "unloadNamespace(XXX)" and "library(XXX)" once more then a call to the R function that was changed will print "Hello world"; i.e. the new code is used. If the above sequence is changed to 2), 3) and then 1), then 4) behaves "as expected" and the new R code is used immediately. As far as I can tell, if via the .onUnload() hook the shared object is unloaded via library.dynam.unload(), changes in the C code take effect no matter whether I perform the above steps in the sequence 1-2-3-4 or 2-3-1-4. My preference is to use the sequence 1-2-3-4 since it seems to be the "more logical and cleaner" sequence; and I have vague memories that I managed to crash R in the past after using 2-3 and then trying to quit R. I am wondering why does it make a difference with respect to R code in which order these steps are done but not with respect to compiled code. Well, I guess I understand why the order does not matter for compiled code, but I do not understand why the order matters for R code. I could not find anything in the documentation that would explain this behaviour, or indicate that this is the intended behaviour. Enlightening comments and/or pointers to where this behaviour is documented would be welcome. Cheers, Berwin =========================== Full address ============================= Berwin A Turlach Tel.: +65 6516 4416 (secr) Dept of Statistics and Applied Probability +65 6516 6650 (self) Faculty of Science FAX : +65 6872 3919 National University of Singapore 6 Science Drive 2, Blk S16, Level 7 e-mail: sta...@nus.edu.sg Singapore 117546 http://www.stat.nus.edu.sg/~statba ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel