Hi all,
I'm not sure whether this is a bug or not, so I think this is the
right place to start with. Consider the following code:
Rcpp::sourceCpp(code='
#include <Rcpp.h>
using namespace Rcpp;
// [[Rcpp::export]]
void print_fun(Function x) {
Rcout << x << std::endl;
}
// [[Rcpp::export]]
void print_env(Environment x) {
Rcout << x << std::endl;
}
')
print_fun(function() {})
print_env(environment())
It compiles and the output from the functions are two addresses. So
far, so good. However, if we try the same for a data frame, the
compilation fails, so we need to define the operator<< as follows:
Rcpp::sourceCpp(code='
#include <Rcpp.h>
using namespace Rcpp;
inline std::ostream& operator<<(std::ostream& out, const DataFrame& df) {
out << "data.frame";
return out;
}
// [[Rcpp::export]]
void print_df(DataFrame x) {
Rcout << x << std::endl;
}
')
print_df(data.frame(x=1))
Now, it compiles and produces the output we defined. Once more, so
far, so good. Now the problem comes when we try to merge the two
examples above, that is:
Rcpp::sourceCpp(code='
#include <Rcpp.h>
using namespace Rcpp;
inline std::ostream& operator<<(std::ostream& out, const DataFrame& df) {
out << "data.frame";
return out;
}
// [[Rcpp::export]]
void print_df(DataFrame x) {
Rcout << x << std::endl;
}
// [[Rcpp::export]]
void print_fun(Function x) {
Rcout << x << std::endl;
}
// [[Rcpp::export]]
void print_env(Environment x) {
Rcout << x << std::endl;
}
')
The compilation fails again due to an ambiguous overload for Function
and Environment types, so that we need to define the operator<< for
these classes too in order to disambiguate and fix this. I suppose it
may happen for other classes too. Is this... expected? Desirable? At
the very least, it is confusing from my point of view.
Regards,
Iñaki
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