[R-pkg-devel] Why doesn't R CMD check warn that globalVariables() is undefined/not imported?

[Henrik Bengtsson]

On Tue, Sep 24, 2019 at 11:13 AM Gábor Csárdi <csardi.gabor using gmail.com> wrote:
>
> I believe that this is because if it is outside of a function, then it
> runs at INSTALL time, and codetools checks the installed code, i.e.
> the function objects typically, and the checks never see the
> globalVariables() call.

That would make sense.  Would you say this is a false negative for 'R
CMD check', that is, should it ideally warn about this?

Personally, I argue that one should use:

utils::globalVariables(...)

or

globalVariables(...)
NAMESPACE: importFrom(utils, globalVariables)

/Henrik

>
> Gabor
>
> On Tue, Sep 24, 2019 at 7:08 PM Henrik Bengtsson
> <henrik.bengtsson using gmail.com> wrote:
> >
> > 'R CMD check' will give a warning that 'speed' is an unknown variable in:
> >
> >   low_speeds <- function(limit) {
> >     subset(datasets::cars, speed <= limit)
> >   }
> >
> > We can tell 'R CMD check' that 'speed' is a false positive by
> > declaring it a "global" variable.  This can be done, by:
> >
> >   low_speeds <- function(limit) {
> >     subset(datasets::cars, speed <= limit)
> >   }
> >   utils::globalVariables("speed")
> >
> > So, far so good. But, why doesn't 'R CMD check' complain about
> > 'globalVariables' not being defined if we use
> >
> >   globalVariables("speed")
> >
> > without utils::* and without having an importFrom("utils",
> > "globalVariables") in the NAMESPACE?
> >
> > For what it's worth, if I add a globalVariables() inside a function
> > definition, e.g.
> >
> >   low_speeds <- function(limit) {
> >     globalVariables("speed")
> >     subset(datasets::cars, speed <= limit)
> >   }
> >   globalVariables("speed")
> >
> > then 'R CMD check' will indeed complain about that inner globalVariables():
> >
> > $ R --vanilla CMD check teeny_0.1.0.tar.gz
> > * using log directory ‘/home/hb/repositories/teeny.Rcheck’
> > * using R version 3.6.1 (2019-07-05)
> > * using platform: x86_64-pc-linux-gnu (64-bit)
> > [...]
> > * checking R code for possible problems ... NOTE
> > low_speeds: no visible global function definition for ‘globalVariables’
> > Undefined global functions or variables:
> >   globalVariables
> > Consider adding
> >   importFrom("utils", "globalVariables")
> > to your NAMESPACE file.
> >
> > Is this an oversight in R CMD check, or is it implicit that the
> > 'utils' package is attached when installing and checking packages and
> > we can use 'utils' objects at the top level of a package?
> >
> > Thanks,
> >
> > Henrik
> >
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