[Rd] Package dependencies and imports

[Prof Brian Ripley]

On Fri, 22 Sep 2006, Martin Maechler wrote:

>>>>>> "Seth" == Seth Falcon <sfalcon at fhcrc.org>
>>>>>>     on Thu, 21 Sep 2006 10:33:06 -0700 writes:
>
>    Seth> Martin Maechler <maechler at stat.math.ethz.ch> writes:
>    >>  I think you should use the new DESCRIPTION field and say
>    >> 'Enhances: rgl'
>    >>
>    >> but I haven't checked if this prevents the warning,
>    >> though I think it should..
>
>    Seth> But is Rcmdr enhancing rgl or being enhanced by rgl?
>
>    Seth> :-( :-(
>
> I think this distinction is not so easily made on a general level.
> I'd say an argument for how you can (should?) think about this
> is the following abstraction:
>
> There are two packages, A and B.
> A's DESCRIPTION has 'Enhances: B'.
> When B is there, A provides extra features.
> In one sense, this always enhances B ("enhance" in the usual
> English meaning), since B's area of application has been
> enlarged by code in A.

Yes, but that is just as true of the raft of packages that Rcmdr has in 
'Suggests'.  I suggested to John, and still think, that 'Suggests: rgl' is 
right.  Rcmdr will work without it, but works better with it and so if you 
are installing Rcmdr you would like to install rgl as well (but it fails 
to install it would not be a major loss).


-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595