On 13-10-20 04:58 PM, Gabor Grothendieck wrote:
On Sun, Oct 20, 2013 at 4:49 PM, Duncan Murdoch
<murdoch.dun...@gmail.com> wrote:
On 13-10-20 4:43 PM, Jonathan Greenberg wrote:
I'm working on an update for my CRAN package "spatial.tools" and I noticed
a new warning when running R CMD CHECK --as-cran:
* checking CRAN incoming feasibility ... NOTE
Maintainer: 'Jonathan Asher Greenberg <spatial-to...@estarcion.net>'
Depends: includes the non-default packages:
'sp' 'raster' 'rgdal' 'mmap' 'abind' 'parallel' 'foreach'
'doParallel' 'rgeos'
Adding so many packages to the search path is excessive
and importing selectively is preferable.
Is this a warning that would need to be fixed pre-CRAN (not really sure
how, since I need functions from all of those packages)? Is there a way
to
import only a single function from a package, if that function is a
dependency?
You really want to use imports. Those are defined in the NAMESPACE file;
you can import everything from a package if you want, but the best style is
in fact to just import exactly what you need. This is more robust than
using Depends, and it doesn't add so much to the user's search path, so it's
less likely to break something else (e.g. by putting a package on the path
that masks some function the user already had there.)
That may answer the specific case of the poster but how does one
handle the case
where one wants the user to be able to access the functions in the
dependent package.
There are two answers to this, depending on how much of the dependent
package you want to make available to the user. If you want most of that
package to be available then this is the (only?) exception to the rule.
From Writing R Extensions:
Field ‘Depends’ should nowadays be used rarely, only for packages
which are intended to be put on the search path to make their
facilities available to the end user (and not to the package itself):
for example it makes sense that a user of package latticeExtra would
want the functions of package lattice made available.
If you really only want to make a couple of functions available then you
can import and export the functions. Currently this has the unfortunate
side effect that you need to document the functions, you cannot just
re-direct to the documentation in the imported package, at least, I have
not figured out how to do that.
Paul
For example, sqldf depends on gsubfn which provides fn which is used
with sqldf to
perform substitutions in the SQL string.
library(sqldf)
tt <- 3
fn$sqldf("select * from BOD where Time > $tt")
I don't want to ask the user to tediously issue a library(gsubfn) too since
fn is frequently needed and for literally years this has not been necessary.
Also I don't want to duplicate fn's code in sqldf since that makes the whole
thing less modular -- it would imply having to change fn in two places
if anything
in fn changed.
______________________________________________
R-devel@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-devel
