Hi All,
I running into some problems using a combination of Rcpp-attributes and
Rcpp-modules to expose a C++ class library, and would appreciate your help.
I am trying to expose to R the constructor of a C++ class template which
accepts a std vector of the template parameter T as input, as shown in the
following toy class A used to replicate the problem:
template <class T> class A {
public:
std::vector<T> vec_of_T;
A( std::vector<T> in_vec );
};
The class and constructor will only be exposed to R as a specific instantiation
of the class A with template parameter T=class B, i.e. A<B>, where B is
implemented in both C++ and R, and the C++ implementation of B has a
constructor B::B(SEXP):
#include <RcppCommon.h>
class B {
public:
int id;
B (SEXP b);
B (int id=-1);
};
/*** R
# Reference Class of B
B_R <- setRefClass( "B_R",
fields = list(id="numeric")
)
*/
template <class T> class A {
public:
std::vector<T> vec_of_T;
A( std::vector<T> in_vec );
};
#include <Rcpp.h>
B::B(SEXP b){
Rcpp::Reference in_b(b);
id=in_b.field("id");
}
B::B(int id){
this->id=id;
}
The idea is to allow an R vector of Reference Class objects B_R to be passed to
the C++ class A<B> constructor. To achieve this I have used the following
Rcpp-modules directly after the preceding code:
using namespace Rcpp;
RCPP_MODULE(testing) {
class_< A<B> >("A")
.constructor< std::vector<B> >()
;
}
I then use Rcpp-attributed sourceCpp() to compile the code from the R prompt,
and generate the R bindings to the C++ class A<B>.
> sourceCpp(file="test.cpp", verbose=TRUE)
>From my understand of section 3.2 in Rcpp-introduction.pdf, and what I could
>glean about the handling of RCPP_MODULE declarations within Rcpp-attribute
>(e.g. help(sourceCpp)), the conversion of "STL vectors of [...] arbitrary
>types that offer a constructor that takes a SEXP" should be supported by Rcpp,
>and Rcpp-attributes should automatically generate wrappers/bindings which
>utilize them.
However, when I run the above sourceCpp command I get the following error which
is stretching my understanding on both C++ and Rcpp:
C:/PROGRA~1/R/R-30~1.1/bin/i386/R CMD SHLIB -o "sourceCpp_42052.dll" "test.cpp"
g++ -m32 -I"C:/PROGRA~1/R/R-30~1.1/include" -DNDEBUG
-I"C:/Users/me/Documents/R/win-library/3.0/Rcpp/include"
-I"d:/RCompile/CRANpkg/extralibs64/local/include" -O2 -Wall -mtune=core2
-c test.cpp -o test.o
In file included from
C:/Users/me/Documents/R/win-library/3.0/Rcpp/include/RcppCommon.h:110:0,
from test.cpp:1:
C:/Users/me/Documents/R/win-library/3.0/Rcpp/include/Rcpp/internal/export.h: In
function 'void Rcpp::internal::export_range(SEXP, InputIterator) [with
InputIterator = __gnu_cxx::__normal_iterator<B*, std::vector<B> >, SEXP =
SEXPREC*]':
C:/Users/me/Documents/R/win-library/3.0/Rcpp/include/Rcpp/internal/Exporter.h:47:17:
instantiated from 'T Rcpp::traits::RangeExporter<T>::get() [with T =
std::vector<B>]'
C:/Users/me/Documents/R/win-library/3.0/Rcpp/include/Rcpp/as.h:83:33:
instantiated from 'T Rcpp::internal::as(SEXP, Rcpp::traits::r_type_generic_tag)
[with T = std::vector<B>, SEXP = SEXPREC*]'
C:/Users/me/Documents/R/win-library/3.0/Rcpp/include/Rcpp/as.h:126:89:
instantiated from 'T Rcpp::as(SEXP) [with T = std::vector<B>, SEXP = SEXPREC*]'
C:/Users/me/Documents/R/win-library/3.0/Rcpp/include/Rcpp/module/Module_generated_Constructor.h:47:43:
instantiated from 'Class* Rcpp::Constructor_1<Class, U0>::get_new(SEXPREC**,
int) [with Class = A<B>, U0 = std::vector<B>, SEXP = SEXPREC*]'
test.cpp:59:1: instantiated from here
C:/Users/me/Documents/R/win-library/3.0/Rcpp/include/Rcpp/internal/export.h:90:4:
error: no matching function for call to 'export_range__dispatch(SEXPREC*&,
__gnu_cxx::__normal_iterator<B*, std::vector<B> >&,
Rcpp::traits::r_type_traits<B>::r_category)'
C:/Users/me/Documents/R/win-library/3.0/Rcpp/include/Rcpp/internal/export.h:90:4:
note: candidates are:
C:/Users/me/Documents/R/win-library/3.0/Rcpp/include/Rcpp/internal/export.h:71:14:
note: template<class InputIterator, class value_type> void
Rcpp::internal::export_range__dispatch(SEXP, InputIterator,
Rcpp::traits::r_type_primitive_tag)
C:/Users/me/Documents/R/win-library/3.0/Rcpp/include/Rcpp/internal/export.h:80:8:
note: template<class InputIterator, class value_type> void
Rcpp::internal::export_range__dispatch(SEXP, InputIterator,
Rcpp::traits::r_type_string_tag)
make: *** [test.o] Error 1
Error in sourceCpp(file = "test.cpp", verbose = TRUE) :
Error 1 occurred building shared library.
Am I missing something in my code?
Thanks in advance,
Luke Domanski.
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