ROOTR_EXPOSED_CLASS(MyFunctor)

R

%%cpp -d

#include<TRInterface.h>
#include<TMath.h>

typedef Double_t (*Function)(Double_t);

//Functor class with the function inside
class MyFunctor{
public:
   MyFunctor() {
      status=false;
      f=TMath::BesselY1;
   }

   void setFunction(Function fun) {
    f=fun;
    status=true;
   }

   Bool_t getStatus(){return status;}

   Double_t doEval(Double_t x) {
      return f(x);
   }

private:
   Function f;
   Bool_t status;
};

%%cpp -d
OOTR_MODULE(MyFunctorModule) {
   ROOT::R::class_<MyFunctor>( "MyFunctor" )
   //creating a default constructor
   .constructor()
   //adding the method doEval to evaluate the internal function
   .method( "doEval", &MyFunctor::doEval )
   .method( "getStatus", &MyFunctor::getStatus)
   ;
}

ROOT::R::TRInterface &r=ROOT::R::TRInterface::Instance();

r["MyFunctorModule"]<<LOAD_ROOTR_MODULE(MyFunctorModule);

r<<"MyFunctor <- MyFunctorModule$MyFunctor";

r<<"u <- new(MyFunctor)";

r<<"print(u$getStatus())";

r<<"print(sprintf('value in R = %f',u$doEval( 1 )))";
std::cout<<"value in ROOT = "<<TMath::BesselY1(1)<<std::endl;

MyFunctor functor;
functor.setFunction(TMath::Erf);
r["functor"]<<functor;

r<<"print(functor$getStatus())";
r<<"print(sprintf('value in R = %f',functor$doEval( 1 )))";
std::cout<<"value in ROOT = "<<TMath::Erf(1)<<std::endl;