[Rcpp-devel] Template and non-template arguments in RCPP_RETURN_VECTOR

[Sven E. Templer]

To create a templated function one can use the macro RCPP_RETURN_VECTOR, e.g:

sourceCpp(code='
#include <Rcpp.h>
template <typename T>
T index_template ( T X )
{
  Rcpp::IntegerVector I(1, 0);
  return X[I];
}
// [[Rcpp::export]]
SEXP index ( SEXP X )
{
  RCPP_RETURN_VECTOR(index_template, X);
}
')
index(letters)
index(c(pi,2,1))


Using a templated and a non-templated argument does not(?) allow use
of the macro, e.g.:

sourceCpp(code='
#include <Rcpp.h>
template <typename T>
T index2_template ( T X, Rcpp::IntegerVector & I )
{
  return X[I];
}
// [[Rcpp::export]]
SEXP index2 ( SEXP X,  Rcpp::IntegerVector & I )
{
  switch(TYPEOF(X)) {
    case STRSXP: return index2_template(Rcpp::Vector<STRSXP>(X), I); break;
    case REALSXP: return index2_template(Rcpp::Vector<REALSXP>(X), I); break;
    case INTSXP: return index2_template(Rcpp::Vector<INTSXP>(X), I); break;
    default: Rf_error("Unsupported type.");
  }
}
')
index2(c(pi,2,1),2)
index2(letters,2)

Is there an easier way that I am missing, than to use switch/TYPEOF ...?
Like RCPP_RETURN_VECTOR2(index_template, X, I).

Thank you for any hint,
Sven.