[R] loading an updated version of a package during an active R session?

[Roger Levy]

Prof Brian Ripley wrote:
> On Wed, 9 Apr 2008, Roger Levy wrote:
> 
>> I am developing a package and I want to be able to load an updated 
>> version of the package from within an active R session.  Suppose,
>> for example, I have a function f within a package X.  In my active
>> R session, I have already loaded X.  Then I change the R source
>> code of f within X and rebuild the package as a .tar.gz file on the
>> command line with
>> 
>> R CMD build X
>> 
>> Within my R session, is there a way to reload X such that the
>> updated definition of f will be used?  I have tried:
>> 
>>> detach("package:X") install.packages("X.tar.gz", repos=NULL,
>>> type="source") library(X)
>> 
>> but this seems to use the old version of f.  Any suggestions would
>> be much appreciated!
> 
> It does work for some packages but not in general.  If the package
> has a namespace, you need to unload that, e.g.
> 
> unloadNamespace("X")
> 
> before library(X) (and that will detach X as well).

Ah, I see -- I was under the mistaken impression that detaching the
package would also get rid of the namespace.  In my particular case,
using unloadNamespace() did the trick properly.

> Note too that many (most?) packages with DLLs do not unload the DLL
> when their namespace is unloaded (or they are detached), in which
> case you can end up with the new R code and the old compiled code

In my case I am developing on OS X so there are no DLLs, but this is a
good proviso to know.  Does the same proviso apply to shared objects in 
Unix and OS X?

Best & many thanks.

Roger

> So without more details or the example asked for in the footer it is
> hard to be explicit about what needs to be done.


-- 

Roger Levy                      Email: rlevy at ucsd.edu
Assistant Professor             Phone: 858-534-7219
Department of Linguistics       Fax:   858-534-4789
UC San Diego                    Web:   http://ling.ucsd.edu/~rlevy