[Rd] declaring package dependencies
murdoch.duncan at gmail.com
Thu Sep 12 19:37:29 CEST 2013
On 12/09/2013 9:38 AM, Michael Friendly wrote:
> I received the following email note re: the vcdExtra package
> > A vcd update has shown that packages TIMP and vcdExtra are not
> > declaring their dependence on colorspace/MASS: see
> > http://cran.r-project.org/web/checks/check_results_vcdExtra.html
> But, I can't see what to do to avoid this, nor understand what has
> changed in R devel.
> Sure enough, CRAN now reports errors in examples using MASS::loglm(),
> using R Under development (unstable) (2013-09-11 r63906)
> > Caesar.mod0 <- loglm(~Infection + (Risk*Antibiotics*Planned),
> Error: could not find function "loglm"
I think this one would be fine if you had library(MASS) or require(MASS)
or (probably best) used MASS::loglm explicitly. It may be that in the
past some other package put MASS on the search list, and that's why it
The distinction is between "loading" and "attaching" a package. Loading
it (which would be done if you had MASS::loglm, or imported it)
guarantees that the package is initialized and in memory, but doesn't
make it visible to the user without the explicit MASS:: prefix.
Attaching it first loads it, then modifies the user's search list so the
user can see it.
Loading is less intrusive, so it's preferred over attaching. Both
library() and require() would attach it.
> In DESCRIPTION I have
> Depends: R (>= 2.10), vcd, gnm (>= 1.0.3)
> and the vcd DESCRIPTION has
> Depends: R (>= 2.4.0), grid, stats
> Suggests: KernSmooth, mvtnorm, kernlab, HSAUR, coin
> Imports: utils, MASS, grDevices, colorspace
> so, in an R 3.0.0 console, library(vcdExtra) loads vcd and its dependencies:
> > library(vcdExtra)
> Loading required package: vcd
> Loading required package: MASS
> Loading required package: grid
> Loading required package: colorspace
> Loading required package: gnm
> Warning messages:
> 1: package ‘vcd’ was built under R version 3.0.1
> 2: package ‘MASS’ was built under R version 3.0.1
> Note: these CRAN errors do not occur on R-Forge, using R version 3.0.1
> Patched (2013-08-21 r63645)
> and the latest devel version (0.5-11) of vcdExtra.
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