[Rd] package check note: no visible global function definition (in functions using Tcl/Tk)

[Prof Brian Ripley]

On Mon, 11 Jun 2007, Seth Falcon wrote:

> Prof Brian Ripley <ripley at stats.ox.ac.uk> writes:
>
>> It seems that is happens if package tcltk is missing from the Depends:
>> list in the DESCRIPTION file.  I just tested with Amelia and homals and
>> that solved the various warnings in both cases.
>
> Adding tcltk to Depends may not always be the desried solution.  If

But I didn't say it was (I didn't mention a solution at all). What I did 
say was that it happened if 'tcltk' was missing (which implies that it 
should have been there), and gave two of the tens of instances of this on 
CRAN.

You may prefer the version now in R-devel: this goes slightly the other 
way in that it loads all the Suggests/Enhances packages and also a dummy 
compatibility package for platform differences.  Neither this nor the 
previous version can test the conditionalization is correct, as the code 
is analysed but no path through it is run.  It is entirely possible that 
the problems flagged are in code that can never be reached: this shows up 
dramatically in examples such as Hmisc with non-R code (for S3 or S4).


> tcltk is already in Suggests, for example, and the intention is to
> optionally provide GUI features, then the code may be correct as-is.
> That is, codetools will issue the NOTEs if you have a function that
> looks like:
>
>   f <- function() {
>     if (require("tckltk")) {
>             someTckltkFunctionHere()
>     } else
>             otherwiseFunction()
>     }
>   }
>
> There are a number of packages in the BioC repository that provide
> such optional features (not just for tcltk) and it would be nice to
> have a way of declaring the use such that the NOTE is silenced.
>
> [Note 1: I don't have any ideas at the moment for how this could
> work.]
>
> [Note 2: Despite the false-positives, I've already caught a handful of
> bugs by reading over these NOTEs and think they provide a lot of value
> to the check process]
>
> + seth
>
>

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595