[Rd] clarification of library/require semantics

[Seth Falcon]

On  4 Nov 2005, ripley at stats.ox.ac.uk wrote:
> I set my standard libraries in R_LIBS, so when I use lib.loc it is
> for experimental things.  So I would neither want the .libPaths
> changed nor be affected if they were.

With the current semantics, if one is testing a _collection_ of
experimental packages that depend on each other, the only way to test
the collection is to modify .libPaths.

Setting lib.loc only allows one to test a single experimental package
against dependencies picked up from R_LIBS.

Robert's proposal, as I understand it, would change the meaning of
lib.loc so that dependencies would be resolved there --- allowing a
collection of experimental packages to be tested against each other.

The current behavior could be replicated in this case by putting a
given experimental package in a library by itself.

Clearly, each choice has a tradeoff.  I understand that if one most
often tests a single independent experimental package, then the
current behavior is most convenient.

My preference is for lib.loc grabbing dependencies because I more
often deal with packages that have dependencies that I want to test
together.


+ seth