On 19/01/2009, at 3:14 PM, Murray Cooper wrote:
I am working on a methodology for qualifying R, for GLP and GCP.
If I quailfy only the base R install, with no contributed packages, it
seems relatively simple to qualify R. However, from time to time I
will want to use a contributed package. If I use a contributed
package,
does it leave anything behind that will be loaded with the next
invocation
of R?
Suppose I run R and use a contributed package and then exit.
Next time I want to run R, for GLP work and will only use base R.
Can I be sure I am only working with base R?
Or do I need to maintain two installations of R, one for use
with GLP/GCP and one for when I want to use contributed packages?
I hope this is clear.
You can make sure that no after-effects are left by
(a) *not* saving your workspace when you quit from R
or (b) removing (or moving) the saved copy (.RData) before
starting your new session
or (c) starting your new session with the --no-restore-data flag
or (d) possibly a few other things.
I.e. the only after effects that a contributed package might leave are
of the form of objects in a saved workspace.
I guess *theoretically* a contributed package could effect changes to
base R
or to other contributed packages via, say, the system() function.
However
this would run into permissions blocks on most systems, and at any
rate would
be unacceptable to the R community and I expect that if a package
were discerned
to do such things it would be removed from CRAN. I am as certain as
I am of
anything that no package currently on CRAN would do such a thing.
It seems to me that it should be possible to build a check for such
unacceptable
behaviour into ``R CMD check''. Would it be paranoiac to do so?
cheers,
Rolf Turner
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