[Rcpp-devel] Initiate NumericMatrix in class constructor from S4 slot

There is no constructor of Matrix tht takes a SlotProxy. You can do it in two steps perhaps. 

SEXP tmp = classS4.slot("M_R") ;
M = tmp ; 

Or use a specific cast: 

M((SEXP)classS4.slot("M_R"));

In any case, you should use an initialisation list in your constructor anyway, something like: 

FirstClass::FirstClass(Rcpp::S4& classS4) : M( (SEXP)classS4.slot("M_R")) {}

Hiwever, i will add the missing constructor if this does not break anything else. 

Romain

Le 6 mars 2013 ? 08:14, Simon Zehnder <szehnder at uni-bonn.de> a ?crit :

Dear Rcpp-Devels,

I am a little confused right now with the following setting:

I have a C++ class with for example the following header

#include <RcppArmadillo.h>

class FirstClass {

  public:
      Rcpp::NumericMatrix M;

      FirstClass(Rcpp::S4& classS4);
      ~FirstClass();
}

Then, in the .cc file I have:

#include <RcppArmadillo.h>
#include "FirstClass.h"

FirstClass::FirstClass(Rcpp::S4& classS4) {

  M(classS4.slot("M_R"));     // array M_R in R
};

FirstClass::~FirstClass(){};

Now, my compiler always gives me an error: 

error: no match for call to ?(Rcpp::NumericMatrix {aka Rcpp::Matrix<14>}) (Rcpp::RObject::SlotProxy)?


Do I have to create the Matrix in the constructor differently? I want to reuse memory allocated in R. Further, could the error be triggered by M_R being an array in R? 

Best 

Simon