Question about selective importing of package functions...

Duncan:

Thanks -- learning something new today -- quick follow-up, will using
the import statements in the NAMESPACE, when a user goes to
install.packages(), auto-install the "dependent" packages the same way
Depends forces?

--j


On Sun, Oct 20, 2013 at 3:49 PM, Duncan Murdoch
<murdoch.duncan at gmail.com <mailto:murdoch.duncan at 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-tools at estarcion.net <mailto: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




--
Jonathan A. Greenberg, PhD
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Global Environmental Analysis and Remote Sensing (GEARS) Laboratory
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