[Rcpp-devel] Defining wrap methods for C++ classes that have data members of Rcpp types

[Douglas Bates]

On looking more closely I can't use cxxfunction with plugin="Rcpp" to
test this because the plugin inserts

#include <Rcpp.h>

before the user includes and some parts in the user includes need to
be declared before Rcpp.h is included.  I'll create a small package.

On Tue, Dec 7, 2010 at 10:06 AM, Douglas Bates <bates at stat.wisc.edu> wrote:
> I'm again trying to define instances of the wrap template for C++
> classes that have data members defined in Rcpp.h
>
> A stand-alone example, which is rather lengthy, is enclosed.  In this
> example I am unsuccessful in using the "intrusive" formulation
> described in the "Extending Rcpp" vignette.  I will try again with the
> "non-intrusive" formulation.  Other suggestions are welcome.
>
> library(Matrix)
> library(inline)
> library(Rcpp)
>
> incl <- '
> #include <RcppCommon.h>
>
> namespace Rcpp {
>     template <int RTYPE> class Vector;
>     template <int RTYPE> class Matrix;
>     class S4;
>     typedef Vector<REALSXP> NumericVector;
>     typedef Vector<INTSXP>  IntegerVector;
>     typedef Vector<VECSXP>  List;
>     typedef Matrix<REALSXP> NumericMatrix;
> }
>
> class dtrMatrix {
> protected:
>    Rcpp::NumericVector d_dat;
>    Rcpp::List d_dimnames;
>    int d_size;                 // must be square
>    bool d_upper;               // true if upper triangular
>    bool d_unit;                // true if unit diagonal
> public:
>    dtrMatrix(Rcpp::S4&) throw (std::runtime_error);
>    operator SEXP();
> };
>
> #include <Rcpp.h>
>
> dtrMatrix::dtrMatrix(Rcpp::S4& xp) throw (std::runtime_error)
>    : d_dat(xp.slot("x")), d_dimnames(xp.slot("Dimnames")) {
>    if (!xp.inherits("dtrMatrix"))
>        throw std::runtime_error("constructor needs S4 class dtrMatrix");
>    IntegerVector dd = xp.slot("Dim");
>    if (dd.size() != 2 || dd[0] != dd[1])
>        throw std::runtime_error("Matrix must be square");
>    d_size = dd[0];
>    std::string uplo = as<std::string>(xp.slot("uplo"));
>    d_upper = (uplo == "U") || (uplo == "u");
>    std::string diag = as<std::string>(xp.slot("diag"));
>    d_unit = (diag == "U") || (diag == "u");
> }
>
> dtrMatrix::operator SEXP() {
>    Rcpp::S4 ans("dtrMatrix");
>    ans.slot("x") = clone(d_dat);
>    ans.slot("Dimnames") = clone(d_dimnames);
>    IntegerVector dd(2);
>    dd[0] = dd[1] = d_size;
>    ans.slot("Dim") = dd;
>    ans.slot("uplo") = d_upper ? "U" : "L";
>    ans.slot("diag") = d_unit ? "U" : "N";
>    return ans;
> }
> '
>
> code <- '
> dtrMatrix x(S4(x_));
> return wrap(x);
> '
> ff <- cxxfunction(signature(x_ = "ANY"), code, incl, plugin="Rcpp")
>
> example("dtrMatrix-class")
> ff(T)
>