On 19/10/2016 4:33 PM, Dirk Eddelbuettel wrote:
On 19 October 2016 at 19:29, Berry Boessenkool wrote:
| A package I am developing will have one additional (not core) function
depending on RCurl.
| To keep dependencies low, I am considering to put RCurl in 'Suggests' instead
of 'Imports'.
| Also, I guess some users / systems may not have libcurl installed.
|
| Then I would write something like
| indexDWD <- function(...)
| {
| if(!requireNamespace("RCurl", quietly=TRUE))
| stop("The R package 'RCurl' is not available. indexDWD can not obtain file
list.\n",
| "install.packages('RCurl') to enable this.")
| ... # otherwise do some nice stuff with RCurl::getURL
| }
|
| Can /should I still have an example tested by CRAN? (I've seen \dontrun used
in similar situations)
| Or should CRAN check never depend on an ftp-server being accessible?
What you have is the correct approach: test _if the package can be loaded_
and if so, proceed. Else skip the test.
Some just put packages in Suggests: and then still assume them be installed.
That's just wrong in my book, though not enforced as a fail by CRAN.
It's officially wrong, but not in our current suite of tests.
I think there would be some discussions on what is acceptable if the
suggested package is missing: I'd argue an error is the right thing if
there isn't an alternate way to give the right answer, but that kind of
error shouldn't cause your package to fail to be accepted. However, we
don't do those tests, because we currently don't have the resources to
do so.
Duncan Murdoch
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