[Rcpp-devel] class methods and R_RegisterCCallable

Serguei Sokol serguei.sokol at gmail.com
Thu Oct 24 16:01:33 CEST 2019


I'am trying to find a way to access class methods of one Rcpp package 
(say pkgM) from C++ code in another one (say pkgA).
If it were simple C++ routines and not class methods, the way is known 
and even automatized. E.g. if I generate pkgM with

Rcpp::Rcpp.package.skeleton("pkgM", module=TRUE)

then in pkgM/src/RcppExports.cpp we can see

static const R_CallMethodDef CallEntries[] = {
     {"_pkgM_rcpp_hello_world", (DL_FUNC) &_pkgM_rcpp_hello_world, 0},

As far as I understand, it registers _pkgM_rcpp_hello_world for use with 
R_GetCCallable from other packages. And it is a consequence of preceding
rcpp_hello_world() with "// [[Rcpp::export]]".
If I add "// [[Rcpp::interfaces(r, cpp)]]" in pkgM/src/rcpp_module.cpp 
it produces pkgM/inst/include/{pkgM.h,pkgM_RcppExports.h} and

static const R_CallMethodDef CallEntries[] = {
     {"_pkgM_RcppExport_registerCCallable", (DL_FUNC) 
&_pkgM_RcppExport_registerCCallable, 0},
but still nothing for methods and functions from RCPP_MODULE.

So my question, what is a canonical way (if defined) to expose class 
methods (via RCPP_MODULE or any other mechanism) in such a way that they 
become callable from C++ code of another package? Am I supposed to 
register them manually in some way using 
_pkgM_RcppExport_registerCCallable()? And if so, how can I retrieve them 
in C++ code of another package?


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