[Rcpp-devel] tracking volatile bug

Gabor Grothendieck has written at  Sat, 22 Nov 2014 19:17:27 -0500

On Sat, Nov 22, 2014 at 1:43 PM, Sokol Serguei<serguei.sokol at gmail.com>
wrote:

Let try to stick with regular rcpp code
(file: matrix_norm.cpp):

//[[Rcpp::depends(RcppArmadillo)]]
#include <RcppArmadillo.h>
using namespace Rcpp;
using namespace arma;

// [[Rcpp::export]]
double nmat(mat A) {
    Function Matrix_norm_r_=Environment("package:Matrix")["norm"];
    double res=as<double>(Matrix_norm_r_(A, "1"));
    return res;
}

When called in R as:

library(Rcpp)
library(Matrix)
sourceCpp("matrix_norm.cpp")
gctorture(TRUE)
nmat(as.matrix(pi))

it gives an error:
Erreur : 'getCharCE' doit ?tre appel? sur un CHARSXP
(my English translation: Error: 'getCharCE' must be called on CHARSXP)

Something was irregular on my side here?
Serguei.

Try replacing the line that sets res with:

    double res=as<double>(Matrix_norm_r_(NumericMatrix(wrap(A)),
CharacterVector::create("1")));

Be sure to try it on a fresh session since errors from prior runs
could have messed up R.

Yes, this version works too.
The least change that leads to a working code that I have found (thanks to
Martin) is

double res=as<double>(Matrix_norm_r_(A, CharacterVector("1")));

but it is still unclear what is wrong with passing a plain string.
In quickref, all examples pass just numbers without any prior conversion
to NumericVector or IntegerVector. Strings are exception to this?

packageVersion("Rcpp")

gctorture(FALSE)
packageVersion("RcppArmadillo")

R.version.string