abstractfactory.cpp

Think in C++ 第二版源码

//: C25:AbstractFactory.cpp
// From Thinking in C++, 2nd Edition
// Available at http://www.BruceEckel.com
// (c) Bruce Eckel 1999
// Copyright notice in Copyright.txt
// A gaming environment
#include <iostream>
using namespace std;

class Obstacle {
public:
  virtual void action() = 0;
};

class Player {
public:
  virtual void interactWith(Obstacle*) = 0;
};

class Kitty: public Player {
  virtual void interactWith(Obstacle* ob) {
    cout << "Kitty has encountered a ";
    ob->action();
  }
};

class KungFuGuy: public Player {
  virtual void interactWith(Obstacle* ob) {
    cout << "KungFuGuy now battles against a ";
    ob->action();
  }
};

class Puzzle: public Obstacle {
public:
  void action() { cout << "Puzzle\n"; }
};

class NastyWeapon: public Obstacle {
public:
  void action() { cout << "NastyWeapon\n"; }
};

// The abstract factory:
class GameElementFactory {
public:
  virtual Player* makePlayer() = 0;
  virtual Obstacle* makeObstacle() = 0;
};

// Concrete factories:
class KittiesAndPuzzles : 
  public GameElementFactory {
public:
  virtual Player* makePlayer() { 
    return new Kitty;
  }
  virtual Obstacle* makeObstacle() {
    return new Puzzle;
  }
};

class KillAndDismember : 
  public GameElementFactory {
public:
  virtual Player* makePlayer() { 
    return new KungFuGuy;
  }
  virtual Obstacle* makeObstacle() {
    return new NastyWeapon;
  }
};

class GameEnvironment {
  GameElementFactory* gef;
  Player* p;
  Obstacle* ob;
public:
  GameEnvironment(GameElementFactory* factory) :
    gef(factory), p(factory->makePlayer()), 
    ob(factory->makeObstacle()) {}
  void play() {
    p->interactWith(ob);
  }
  ~GameEnvironment() {
    delete p;
    delete ob;
    delete gef;
  }
};

int main() {
  GameEnvironment 
    g1(new KittiesAndPuzzles),
    g2(new KillAndDismember);
  g1.play();
  g2.play();
} ///:~