public:

typedef Environment_Impl<StoragePolicy> Environment ;

typedef Promise_Impl<StoragePolicy> Promise ;

Dots_Impl( Environment env){

SEXP dots = env.find("...") ;

while(dots != R_NilValue){

promises.push_back(CAR(dots)) ;

dots = CDR(dots);

}

}

inline int size() const {

return promises.size() ;

}

inline Promise& promise(int i) {

return promises[i] ;

}

inline Environment environment(int i){

return promises[i].environment() ;

}

private:

std::vector<Promise> promises ;