作者：未知 来源：月光软件站 加入时间：2005-2-28　月光软件站

#include

class CollisionWithUnknownObject {
public:
 CollisionWithUnknownObject()
 {
     std::cout << "unknown error" << std::endl;
 }
 //...
};

class GameObject {
public:
 virtual void collide(GameObject& otherObject) = 0;
 //...
};

//The class SpaceShip Declaration
class SpaceShip: public GameObject {
public:
 virtual void collide(GameObject& otherObject);
 virtual void hitSpaceShip(GameObject& spaceShip);
 virtual void hitSpaceStation(GameObject& spaceStation);
 virtual void hitAsteroid(GameObject& asteroid);
 //...
 
private:
 typedef void (SpaceShip::*HitFunctionPtr)(GameObject& what);
 static HitFunctionPtr lookup(GameObject& what); 
 typedef map< string, HitFunctionPtr > HitMap;
    static HitMap* initializeCollisionMap();
};

//The class SpaceStation Declaration
class SpaceStation: public GameObject {
public:
 virtual void collide(GameObject& otherObject);
 virtual void hitSpaceShip(GameObject& otherObject);
 virtual void hitSpaceStation(GameObject& otherObject);
 virtual void hitAsteroid(GameObject& otherobject);
 //...
private:
 typedef void (SpaceStation::*HitFunctionPtr)(GameObject& what);
 static HitFunctionPtr lookup(GameObject& what);
 typedef map< string, HitFunctionPtr > HitMap;
 static HitMap* initializeCollisionMap();
};

//The class Asteroid Declaration
class Asteroid: public GameObject {
public:
 virtual void collide(GameObject& otherObject);
 virtual void hitSpaceShip(GameObject& otherObject);
 virtual void hitSpaceStation(GameObject& otherObject);
 virtual void hitAsteroid(GameObject& otherobject);
 //...

private:
 typedef void (Asteroid::*HitFunctionPtr)(GameObject& what);
 static HitFunctionPtr lookup(GameObject& what);
 typedef map< string, HitFunctionPtr > HitMap;
 static HitMap* initializeCollisionMap();
};

//The class SpaceShip Definition
void SpaceShip::collide(GameObject& otherObject)
{
    HitFunctionPtr hfp = lookup(otherObject);  //查找要调用的函数
    if(hfp)
    {
        (this->*hfp)(otherObject);
    }
    else
    {
        throw CollisionWithUnknownObject();
    }
}

SpaceShip::HitFunctionPtr
SpaceShip::lookup(GameObject& what)
{
    //不好，会有付出拷贝赋值的代价
    //static HitMap collisionMap = initializeCollisioniMap(); 
   
    //用一个Smart Pointer
    static auto_ptr collisionMap(initializeCollisionMap());
 
 HitMap::iterator mapEntry = collisionMap->find(typeid(what).name());
   
    // 如果查找失败，mapEntry == collisionMap.end()；
    if(mapEntry == collisionMap->end())
        return 0;
     
    // 如果找到了，mapEntry会指向一个完全的map入口，
 // 它是一个(string, HitFunctionPtr)对。我们只想要
 // 它的第二部分，所以这是我们返回的
    return (*mapEntry).second;
}

SpaceShip::HitMap*
SpaceShip::initializeCollisionMap()
{
    HitMap *phm = new HitMap;

    //这里书中直接就是（*phm["SpaceShip"] = &hitSpaceShip;
    //而我用的是Dev-C++编译器，结果我发现
    // typeid（SpaceShip）.name()并不仅仅是SpaceShip,而是128SpaceShip
    // 所以我做了如下修改
    (*phm)[typeid(SpaceShip).name()] = &SpaceShip::hitSpaceShip;
 (*phm)[typeid(SpaceStation).name()] = &SpaceShip::hitSpaceStation;
 (*phm)[typeid(Asteroid).name()] = &SpaceShip::hitAsteroid;
 
 return phm;
}

void SpaceShip::hitSpaceShip(GameObject& spaceShip)
{
 SpaceShip& otherShip = dynamic_cast(spaceShip);

 std::cout << "SpaceShip collide with SpaceShip" << std::endl;
}

void SpaceShip::hitSpaceStation(GameObject& spaceStation)
{
 SpaceStation& station = dynamic_cast(spaceStation);

 std::cout << "SpaceShip collide with SpaceStation" << std::endl;
}

void SpaceShip::hitAsteroid(GameObject& asteroid)
{
 Asteroid& theAsteroid = dynamic_cast(asteroid);

 std::cout << "SpaceShip collide with Asteroid" << std::endl;
}

//The class SpaceStation Definition
void SpaceStation::collide(GameObject& otherObject)
{
 HitFunctionPtr hfp = lookup(otherObject);
 if(hfp)
 {
  (this->*hfp)(otherObject);
 }
 else
 {
  throw CollisionWithUnknownObject();
 }
}

SpaceStation::HitFunctionPtr
SpaceStation::lookup(GameObject& what)
{
 static auto_ptr collisionMap(initializeCollisionMap());
 HitMap::iterator mapEntry = collisionMap->find(typeid(what).name());

 if(mapEntry != collisionMap->end())
  return (*mapEntry).second;
}

SpaceStation::HitMap*
SpaceStation::initializeCollisionMap()
{
 HitMap * pfm = new HitMap;
 (*pfm)[typeid(SpaceShip).name()] = &SpaceStation::hitSpaceShip;
 (*pfm)[typeid(SpaceStation).name()] = &SpaceStation::hitSpaceStation;
 (*pfm)[typeid(Asteroid).name()] = &SpaceStation::hitAsteroid;

 return pfm;
}

void SpaceStation::hitSpaceShip(GameObject& otherObject)
{
 SpaceShip& ship  = dynamic_cast (otherObject);
 std::cout << "SpaceStation collide with SpaceShip" << std::endl;
}

void SpaceStation::hitSpaceStation(GameObject& otherObject)
{
 SpaceStation& otherSpaceStation  = dynamic_cast (otherObject);
 std::cout << "SpaceStation collide with SpaceStation" << std::endl;
}

void SpaceStation::hitAsteroid(GameObject& otherObject)
{
 Asteroid& theAsteroid  = dynamic_cast (otherObject);
 std::cout << "SpaceStation collide with Asteroid" << std::endl;
}

//The class Asteroid Definition
void Asteroid::collide(GameObject& otherObject)
{
 HitFunctionPtr hfp = lookup(otherObject);
 if(hfp)
 {
  (this->*hfp)(otherObject);
 }
 else
 {
  throw CollisionWithUnknownObject();
 }
}

Asteroid::HitFunctionPtr
Asteroid::lookup(GameObject& what)
{
 static auto_ptr< HitMap > collisionMap(initializeCollisionMap());
 HitMap::iterator mapEntry = collisionMap->find(typeid(what).name());

 if(mapEntry != collisionMap->end())
  return (*mapEntry).second;
}

Asteroid::HitMap*
Asteroid::initializeCollisionMap()
{
 HitMap *pfm = new HitMap;
 (*pfm)[typeid(SpaceShip).name()] = &Asteroid::hitSpaceShip;
 (*pfm)[typeid(SpaceStation).name()] = &Asteroid::hitSpaceStation;
 (*pfm)[typeid(Asteroid).name()] = &Asteroid::hitAsteroid;

 return pfm;
}

void Asteroid::hitSpaceShip(GameObject& otherObject)
{
 SpaceShip & ship = dynamic_cast (otherObject);
 std::cout << "Asteroid collide with SpaceShip" << std::endl;
}

void Asteroid::hitSpaceStation(GameObject& otherObject)
{
 SpaceStation & station = dynamic_cast (otherObject);
 std::cout << "Asteroid collide with SpaceStation" << std::endl;
}

void Asteroid::hitAsteroid(GameObject& otherObject)
{
 Asteroid & otherAsteroid = dynamic_cast (otherObject);
 std::cout << "Asteroid collide with Asteroid" << std::endl;
}

int main()
{
 GameObject *g = new SpaceShip;
 GameObject *h = new SpaceStation ;
 GameObject *a = new Asteroid;
 g->collide(*a);
 g->collide(*h);
 h->collide(*g);
 h->collide(*a);
 a->collide(*g);
 a->collide(*h);

system("pause");

}

该程序在winXP Professinal + Dev-C++上通过

我在vc.net上也进行了编译，可是总是在dynamic_cast  处出现错误，不知道为什么？

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