R devel - Oct 2013 - Question about selective importing of package functions...

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-tools@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?

--j

-- 
Jonathan A. Greenberg, PhD
Assistant Professor
Global Environmental Analysis and Remote Sensing (GEARS) Laboratory
Department of Geography and Geographic Information Science
University of Illinois at Urbana-Champaign
259 Computing Applications Building, MC-150
605 East Springfield Avenue
Champaign, IL  61820-6371
Phone: 217-300-1924
http://www.geog.illinois.edu/~jgrn/
AIM: jgrn307, MSN: jgrn307@hotmail.com, Gchat: jgrn307, Skype: jgrn3007

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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-tools at
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.)

Duncan Murdoch