RcppExposedClass

// [[Rcpp::plugins("cpp11")]]

#include <ostream>
#include <iterator>
#include <RcppCommon.h>

class BadIter;
RCPP_EXPOSED_CLASS(BadIter)

#include <Rcpp.h>

using namespace Rcpp;

class BadIter {
public:
  std::vector< int > vec;
  std::vector< int >::iterator vec_iter;
  
  void print_addr()
  {
    std::cout << "  vec.begin addr: " << std::addressof(*vec.begin())
              << std::endl
              << "   vec_iter addr: " << std::addressof(*vec_iter)
              << std::endl;
  }
  
  BadIter(int len) : vec(len), vec_iter( vec.begin() )
  {
    std::cout << "Initializing: " << std::endl;
    print_addr();
  }
  
  std::vector< int > get()
  {
    std::cout << "Accessing: " << std::endl;
    print_addr();
    std::cout << "Reset: " << std::endl;
    vec_iter = vec.begin();
    print_addr();
    return vec;
  }
}; // end class: BadIter

BadIter make_BadIter( int n ) { return BadIter(n); }

RCPP_MODULE(BadIter){
  class_< BadIter >("BadIter")
    .constructor< int >()
    .method( "access", &BadIter::get )
  ;
  function( "make_BadIter", &make_BadIter );
}

// [[Rcpp::export]]
void rcpp_BadIter(int n)
{
  auto bi = BadIter(n);
  bi.get();
}

/*** R
# Via Rcpp
rcpp_BadIter(1)

# Via R
bi <- make_BadIter(1)
bi$access( )

# Setting the vec_iter to vec_begin _after_ the constructor has completed.
bi$access( )

*/