On 03/08/2016 5:36 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 don't set CRAN policy, but I would say yes. Problem 1 limits your package to systems using compilers that support those antiquated headers; R tries very hard to be portable across many systems. Problem 2 makes R potentially unstable.

Duncan Murdoch

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)?


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