[Rd] Rcmdr package dependencies

[John Fox]

Dear Uwe,

> -----Original Message-----
> From: Uwe Ligges [mailto:ligges at statistik.tu-dortmund.de]
> Sent: September-22-09 2:17 PM
> To: John Fox
> Cc: r-devel at r-project.org
> Subject: Re: [Rd] Rcmdr package dependencies
> 
> 
> 
> John Fox wrote:
> > Dear r-devel members,
> >
> > My Rcmdr package "depends" on several other packages (tcltk, grDevices,
> > utils, and car) and "suggests" a number of others (abind, aplpack,
> > colorspace, effects, foreign, grid, Hmisc, lattice, leaps, lmtest, MASS,
> > mgcv, multcomp, nlme, nnet, relimp, rgl, and RODBC). The reason for the
> > distinction is that I don't want all of these packages to load when the
> > Rcmdr loads; rather, the "suggested" packages are loaded as they're
needed.
> > But all of the packages -- both those under "depends" and those under
> > "suggests" -- really are necessary for all of the features of the Rcmdr
to
> > work. For example, if the "leaps" package is absent, then the "Subset
model
> > selection" item in the "Models" menu is suppressed.
> >
> > This arrangement works reasonably well, but it makes it awkward to
install
> > the Rcmdr. If the user issues the command install.packages("Rcmdr"),
then
> > the "suggested" packages aren't installed. On the other hand, if the
user
> > issues the command install.packages("Rcmdr", dependencies=TRUE), which
is
> > what I currently recommend, then "suggested" packages are installed
> > recursively, causing dozens of packages, most of them actually
unnecessary,
> > to be installed. This issue has been growing more acute, and at this
point
> > even with a fast Internet connection it takes quite a while for all of
the
> > dependencies to download and install.
> >
> > I wonder whether I've missed something. Is there a way for me to arrange
> the
> > Rcmdr package dependencies so that only the necessary packages (those
> > currently listed under both "depends" and "suggests" and the packages on
> > which they "depend") are installed along with the Rcmdr, but the
currently
> > "suggested" packages aren't loaded when the Rcmdr loads?
> 
> 
> 
> Dear John,
> 
> no, this is not possible.
> 
> Consider your package A (or Rcmdr) suggests B that suggests C.
> Then A::foo uses the function B::bar which only works if C::dep is
> present. B works essentially without C but it requires C just to make
> bar work. Then this means your A::foo won't work if C is not installed
> and you won't get it with the setup mentioned above.
> 
> In summary, I fear what you want might work well *now* (by chance), but
> it does not work in general.

I agree that what I want to do isn't bullet-proof. I think, however, that in
most, if not all, cases, the Rcmdr dialogs will work even if packages
suggested by currently directly suggested packages were not installed. In
fact, this is what happens when a package is installed with the default
dependencies=FALSE. If it turns out that some such indirect dependency is
actually necessary, I could add that package to those directly suggested
(were such a mechanism possible). I'd save users a lot of downloads at the
price of occasionally having to specify a dependency explicitly.

Thanks,
 John

> 
> Best wishes,
> Uwe
> 
> 
> 
> 
> 
> 
> > Any help would be appreciated.
> >
> > John
> >
> > ------------------------------
> > John Fox, Professor
> > Department of Sociology
> > McMaster University
> > Hamilton, Ontario, Canada
> > web: socserv.mcmaster.ca/jfox
> >
> > ______________________________________________
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