Le 6 mai 2014 à 08:45, Florian Burkart <florian.burk...@gmail.com> a écrit :
> Hi everyone (and Dirk),
>
> Second attempt on corrected email list.
>
> I have been trying to extend Rcpp with my own wrap and as templates.
>
> Two issues:
>
> 1) I need to explicitly call wrap. Is that expected?
>
> So for example I wrote this specialization:
This is not a specialization, just another overload. You need to write a
specialization, as in:
namespace Rcpp{
template<> SEXP wrap<std::vector< TimedOptDouble > >
(std::vector<TimedOptDouble> const& entries) { … }
}
> template<> SEXP Rcpp::wrap(std::vector<TimedOptDouble> const& entries) {
> std::vector<double> sec_times;
> std::vector<double> doubles;
> for(auto const& entry : entries)
> {
> sec_times.push_back(entry.GetTime().Seconds());
> TimedOptDouble::OptDouble opt_double(entry.GetOptDouble());
> if(opt_double)
> doubles.push_back(*opt_double);
> else
> doubles.push_back(R_NaReal);
> }
> return List::create(
> Named( "Time" ) = sec_times,
> Named( "Value" ) = doubles);
> }
>
> First of all, this returns what I believe to be a Rcpp::List object, which
> seems to be converted implicitly to a SEXP. This is the typical behaviour I
> know.
>
> Unfortunately, when making use of this template, it doesn't work implicitly,
> but I need to explicitly call it.
>
> So for example
>
> SEXP GetSunPositions(SEXP a) {
> std::vector<TimedOptDouble> sun_positions;
> ...
> return wrap(sun_positions);
> }
>
> works, where as
>
> return sun_positions;
>
> as last line doesn't. Am I doing something wrong here? I did do the
> declaration before including <Rcpp.h>.
This should work if you return a std::vector< TimedOptDouble > from your
function, as in:
std::vector< TimedOptDouble > GetSunPositions(SEXP a) { … }
> 2) How to make as work for own types in containers
>
> The other way around, one can return a std::vector<double> implicitly, but
> how do I return std::vector<MyType>? I tried to define
>
> template<> MyType as(SEXP);
>
> But that didn't help, e.g. I had to write my own
>
> template<> std::vector<MyType> as(SEXP);
This is the easiest way. A more general way would need you to express how to
handle containers of MyType, but that requires defining some traits classes etc
… not sure it is worth the effort.
But again, you’d need to actually write a specialization: template<>
std::vector<MyType> as< std::vector<MyType> > (SEXP);
Romain
> Thanks for help
>
> Florian
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