RcppでRにポインタを返す

ここ http://lists.r-forge.r-project.org/pipermail/rcpp-devel/2011-August/002667.html にあるまんま

#include "Rcpp.h"

using namespace Rcpp;

RcppExport SEXP getIntPointer(){
     int *test = new int; *test = 6;

     XPtr<int> retVal(test) ;
     return retVal ;
}

RcppExport SEXP doubleIntPointer(SEXP test){
     XPtr<int> test2(test) ;
     return wrap( *test2 * 2 ) ;
}

> dyn.load("RcppPointer.so")
> (x <- .Call("getIntPointer"))
<pointer: 0x2182740>
> (y <- .Call("doubleIntPointer", x ))
[1] 12
> dyn.unload("RcppPointer.so")