Apologies if I'm telling you something you already know:

By default, fda::CRAN() uses the presence of environment variables matched by the regexp "^_R_" as a heuristic to decide whether it's being running on CRAN.

testthat::skip_on_cran() calls testthat::on_cran() to look for an environment variable called NOT_CRAN equal to "true". The devtools::check() machinery automatically sets this variable.


So: fda::CRAN() depends on breakable assumptions, defaults to FALSE in an empty environment. skip_on_cran() defaults to TRUE in an empty environment (but defaults to FALSE in a devtools::check() environment).


On 12/12/20 2:19 PM, Spencer Graves wrote:
      I have tests in my code to detect when something like that is not available.


      I also have code in "\examples" to skip tests that would encounter that.


      Hadley's "testthhat:skip_on_cran" is supposed to suppress tests like that on CRAN.  I have so far failed to understand how to use this function that Hadley wrote.  Instead, I use things like the following:


if(!fda::CRAN()){
# Code that I want to run everyplace that's NOT CRAN


}


      When I wrote "fda::CRAN", I was told that I shouldn't do it, but I didn't see a better option, and I've been using it for several years now without being given a reason to discontinue using it or (better?) being given an alternative that seems better to me.


       Spencer


On 2020-12-12 12:40, Michael L Friendly wrote:
Thanks, Dirk

Just to clarify--
In my packages, candisc, heplots, vcdExtra I have mostly 2D graphic methods, but some 3D methods that use
rgl.  I therefore put rgl into Suggests:

Could I solve this by making rgl a Depends: ?

-Michael


-----Original Message-----
From: Dirk Eddelbuettel <e...@debian.org>
Sent: Saturday, December 12, 2020 12:46 PM
To: Michael L Friendly <frien...@yorku.ca>
Cc: r-package-devel@R-project.org; Prof Brian Ripley <rip...@stats.ox.ac.uk> Subject: Re: [R-pkg-devel] CRAN packages suggesting other packages but not using them conditionally


On 12 December 2020 at 16:24, Michael L Friendly wrote:
| I got the email below concerning 3 of my packages but wonder if they
| are false alarms or if not, how to locate & fix the problem.
|
|     This concerns packages: ...
|
|     Suggested packages should be used conditionally: see  1.1.3.1 of 'Writing R Extensions'.  Some of these are hard to install on a platform without X11 such as M1 Macs: see the logs at https://www.stats.ox.ac.uk/pub/bdr/M1mac/.
|
|     You can check all of the suggested packages by setting environment variable _R_CHECK_DEPENDS_ONLY_=true  -- see https://cran.r-project.org/doc/manuals/r-devel/R-ints.html#Tools .
|
| Is this a false alarm?
|
| In each case, the outfile contains:
|
|     * checking package namespace information ... OK
|     * checking package dependencies ... NOTE
|     Package suggested but not available for checking: 'rgl'
|
| indicating that rgl is not avaiable on the testing machine.  Then,
| when checking examples an error is triggered when an example calls something that requires rgl.
|
|     >
|     > heplot3d(Adopted.mod, hypotheses=list("Reg"=c("AMED", "BMIQ")),
|     +         col = c("red", "blue", "black", "gray"), wire=FALSE)
|     Loading required namespace: rgl
|     Failed with error:  'there is no package called 'rgl''
|     Error in heplot3d.mlm(Adopted.mod, hypotheses = list(Reg = c("AMED", "BMIQ")),  :
|       rgl package is required.
|     Calls: heplot3d -> heplot3d.mlm
|     Execution halted
|
| Yet, heplot3d seems to contain the required way to refer to the suggested rgl package:
|
|                 if (!requireNamespace("rgl")) stop("rgl package is
| required.")
|
| So, I'm mystified.  Can anyone help?

This is not conditional use in the sense of my reading of WRE.

What you have here is essentially an "assert()" and equivalent to
   stopifnot(requireNamespace("rgl"))
which, in turn, is equivalent to a strong Depends or Imports as your package will experience a _critical error_ triggered by `stop()` if rgl is missing.

The idea of a conditional use is to, well, be conditional. Below I make use of Rcpp if is present, but it is only a suggests:

   ## see the source files in the snippets/ directory of the package
   ## check for (optional, only in Suggests:) Rcpp, and also wrapped in a
   ## dontrun as it takes 10s at CRAN (yet only 3.5 here) yielding a NOTE
   if (requireNamespace("Rcpp", quietly=TRUE)) {
       Rcpp::sourceCpp(system.file("snippets", "convolveExample.cpp", package="tidyCpp"))
   }

If the _suggested_ package is present, it is used. If not we quietly move on. (It's not the full story as the compilation occassionally takes longer, Windows complained so all this is now in a \dontrun{} block too. But the idea is generic and there are many more examples to be found.)

Hope this helps,  Dirk

--
https://dirk.eddelbuettel.com | @eddelbuettel | e...@debian.org
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