Simple.cpp

#include <Rcpp.h>
using namespace Rcpp;

class Simple {
    double x;

  public:
    Simple(double x_): x(x_) {}

    Simple(SEXP x_): {

    }

    double times (double i) const {
      return x * i;
    }

    operator SEXP() {

    }

};

RCPP_MODULE(SimpleModule) {
  class_<Simple>( "Simple")
  .constructor<double>()
  .const_method("times", &Simple::times)
  ;
}

// [[Rcpp::export]]
double times2(const Simple& x) {
  return x.times(2);
}

// [[Rcpp::export]]
Simple two() {
  return Simple(2);
}

/*** R


s1 <- Simple$new(5)
s2 <- two()

s1$times(2)
s2$times(2)

times2(s1)
times2(s2)

*/