如何将我写入的对象传递给另一个类的构造函数？

Question

I am implementing a Duplicator class that will allow me to duplicate Game objects. I need to be able to create an identical Game object to the one I have. This is exists within a larger implementation of a board game with several other classes such as Board and Space.

I have two files for the Duplicator class:

Duplicator.h

#ifndef DUPLICATOR_H
#define DUPLICATOR_H

#include <Rcpp.h>
#include <stack>
#include "Game.h"

using namespace Rcpp;


class Duplicator {
private:
  Game gameObj = Game(5);
public:
  Duplicator(Game g);
  // Game genDuplicate();
};
#endif

Duplicator.cpp

#include <Rcpp.h>
#include <vector>
#include "Game.h"
#include "Duplicator.h"

using namespace Rcpp;




Duplicator::Duplicator(Game g){
  gameObj = g;
}



RCPP_EXPOSED_CLASS(Duplicator)
  RCPP_MODULE(duplicator_cpp) {

    class_<Duplicator>("Duplicator")
    .constructor<Game>()
    ;

The error I keep getting is:

no matching constructor for initialization of 'Game'

The game class is contained in two files.

Game.h

#ifndef GAME_H
#define GAME_H

#include <Rcpp.h>

using namespace Rcpp;

class Game {
private:
  int id;
public:
  Game(int n);
};

#endif

Game.cpp

#include <Rcpp.h>
#include "Game.h"

using namespace Rcpp;

Game::Game(int n){
  id = n;
}


RCPP_EXPOSED_CLASS(Game)
  RCPP_MODULE(game_cpp) {

    class_<Game>("Game")
    .constructor<int>()
    ;
  }

I'm not quite sure what I need to do. It seems like I need to supply a constructor for Game in the Duplicator class.

Answer 1

You have to move RCPP_EXPOSED_CLASS(...) to the header file, at least when you want to use that class as an argument or return type in other compilation units. Otherwise the compiler does not know that eg Game can be converted to a SEXP and vice versa.