I want to expose to R several C++ classes from a library with Rcpp
modules. I'm trying to imitate a similar set of Python modules that were
made for the same library.
In Boost.Python, with .def it is possible to specify the
return_value_policy. Is it also possible to do this in a straight forward
way with Rcpp modules when exposing C++ class methods?
The following simplified example illustrates a problem I face with using
Rcpp modules. When R deletes 'res', R crashes shortly after (a segfault?).
With a Python module, this kind of problem apparently doesn't come about by
setting in .def the following:
return_value_policy<reference_existing_object>()
Is there an easy way to get around this problem with Rcpp modules with
minimal code?
#include <Rcpp.h>
using namespace Rcpp;
class A {
public:
A(int x_) : x(x_){}
int x;
};
class B {
public:
B():m_A(10) {}
A get_an_A(){
A an_A(3);
return an_A;
}
A * get_member_A() { return & m_A; }
private:
A m_A;
};
RCPP_EXPOSED_CLASS(A)
RCPP_EXPOSED_CLASS(B)
RCPP_MODULE(AB_mod){
using namespace Rcpp ;
class_<A>("A")
.constructor<int>()
.field("x", &A::x)
;
class_<B>("B")
.constructor()
.method("get_an_A",&B::get_an_A)
.method("get_member_A", &B::get_member_A)
;
}
------------------------
R code:
A_eg <- new(A, 10)
B_eg <- new(B)
res <- B_eg$get_member_A()
rm(res)
# R crashes shortly after running further commands ...
# How can this error be prevented?
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