Hi Ege,
For writing to standard output/error, you can use Rcout or Rcerr
(defined by Rcpp; they even have a vignette showing how to use it in the
Rcpp gallery). Alternatively, if you're using C code, you can replace
printf by Rprintf (this is explained in Writing R extensions, section 6.5).
For abort, you can use error() instead (this is documented in WRE,
section 6.2).
Hope this helps,
Max
On 2016-08-03 03:36 PM, Ege Rubak wrote:
Hi,
I would like to port Google's s2-library for spherical geometry (see
e.g. https://github.com/micolous/s2-geometry-library for a fork on
GitHub). It is not a standard library that can easily be installed on
various systems, so I would like to include the source code in the R
package. The catch is that I would like to modify the source code as
little as possible :-)
I have package everything and added configure scripts and a tiny
R-function that calls one of the C++-functions (using the antiquated
.C interface for now -- that will of course be changed) in this repo:
https://github.com/spatstat/s2
It compiles into a working package on Ubuntu (travis-ci + my laptop),
OSX (travis-ci), and Windows (appveyor + my surface pro), but R CMD
check produces some warnings (and a note about the size of the shared
object, but I assume that is less important).
The main things seem to be related to (travis log is at
https://travis-ci.org/spatstat/s2/jobs/149578339):
1. Deprecated C++ headers <ext/hash_set> and <ext/hash_map>.
2. Compiled code that calls entry points which might terminate R or
write to stdout/stderr.
Is it hopeless to get on CRAN with warnings like these?
I'm not very used to writing C/C++ code, but I guess 1. can be fixed
by a few sed commands with the replacement headers and corresponding
new function names. Point 2. can probably also be fixed with a
reasonable effort, but I haven't investigated yet, and I would like an
opinion from the list before spending more time on this. In more
generality the question could be phrased something like:
"When including C++ code from an upstream library which you do not
control should R CMD check be completely spotless or is some
flexibility to be expected in these circumstances?"
Cheers,
Ege
PS: Extra question (prehaps particularly aimed at Dirk): When I will
actually start to use the C++ library I expect it could be beneficial
to use Rcpp. I have seen RcppModules mentioned somewhere, and I wonder
if such an external C++ library would make sense to interface via
RcppModules (again aiming at changing upstream sources as little as
possible)?
--
-----------------------------------------------------------------
Maxime Turgeon, PhD candidate
Department of Epidemiology, Biostatistics and Occupational Health
McGill University
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