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

[Romain Francois]

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 à 08:14, Simon Zehnder <szehnder at uni-bonn.de> a écrit :

> 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
> 
> 
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