c++ - 为什么双重分派(dispatch)在 C++ 中不起作用？

Question

#include<iostream.h>
#include<conio.h>

using namespace std;

class SpaceShip {};
class GiantSpaceShip : public SpaceShip {};

class Asteroid {
public:
  virtual void CollideWith(SpaceShip *) {
    cout << "Asteroid hit a SpaceShip" << endl;
  }
  virtual void CollideWith(GiantSpaceShip *) {
    cout << "Asteroid hit a GiantSpaceShip" << endl;
  }
};

class ExplodingAsteroid : public Asteroid {
public:
  virtual void CollideWith(SpaceShip *) {
    cout << "ExplodingAsteroid hit a SpaceShip" << endl;
  }
  virtual void CollideWith(GiantSpaceShip *) {
    cout << "ExplodingAsteroid hit a GiantSpaceShip" << endl;
  }
};



int main()
{
  SpaceShip * s = new GiantSpaceShip();    
  Asteroid * a = new ExplodingAsteroid();
  a->CollideWith(s);  
  getch();  

 return 0;   
}

如何在 C++ 中启用双重分派(dispatch)？

Answer 1

这不是单次分派(dispatch)而是双分派(dispatch):您希望该方法既取决于调用它的对象的实际/实际类型，也取决于参数的实际/实际类型.

此问题可以通过 Visitor design pattern 解决.