difference between sourceCpp and Rcpp.package.skeleton

Question

#include <Rcpp.h>
using namespace Rcpp;


// [[Rcpp::export]]
NumericVector condSumRcpp(NumericVector x, NumericVector y, LogicalVector z) {

  int n = x.length();
  int sumLength = sum(z);

  NumericVector res(sumLength);
  int j=0;

  for(int i = 0; i < n; i++) {
    if (!z[i]) continue;
    res[j] = x[i] + y[i];
    j+=1;
  }

  return wrap(res);
 }

This works fine when I use sourceCpp. However when I use

Rcpp.package.skeleton("testRcpp",
  example_code = FALSE,
  cpp_files="utils.cpp",
  module=FALSE
)

and build the package with R CMD INSTALL --build testRcpp I get

Error in .Call("testRcpp_condSumRcpp", PACKAGE = "testRcpp", x, y, z) : 
  "testRcpp_condSumRcpp" not available for .Call() for package "testRcpp"

If I do the same process with

// [[Rcpp::export]]
NumericVector colMaxRcpp(NumericMatrix X) {

    int ncol = X.ncol();
    NumericVector res(ncol);

    for (int col = 0; col < ncol; col++){
        res[col]=Rcpp::max(X(_, col)); 
    }

    return wrap(res);
}

then it works!

Answer 1

You cannot randomly mix Attributes and Rcpp.package.skeleton().

I usually create an empty package first (via Rcpp.package.skeleton() or the corresponding feature in RStudio) and then add my function. Call compileAttributes() and you should be good.