【Python基础】lpthw - Exercise 43 基本的面向对象分析和设计

1. A game

 from sys import exit
 from random import randint
 from textwrap import dedent     # 使可以使用三引号型的字符串

 # 具体实现了场景间的切换
 class Engine(object):

     def __init__(self, scene_map):
         self.scene_map = scene_map

     def play(self):
         current_scene = self.scene_map.opening_scene()  # 初始场景的类
         last_scene = self.scene_map.next_scene('finished')

         while current_scene != last_scene:
             next_scene_name = current_scene.enter()     # 返回一个场景的名字
             current_scene = self.scene_map.next_scene(next_scene_name)

         # 确保print出最后一个场景
         current_scene.enter()

 # 各场景共有的父类
 class Scene(object):

     def enter(self):
         pass

 # 具体的每个场景，其中定义了一些说明和交互
 class Death(Scene):

     quips = ["You died.", "Please try again.", "That's not very good."] # 类变量，可以通过类名调用

     def enter(self):
         print(Death.quips[randint(0,2)])
         exit(1)

 class CentralCorridor(Scene):

     def enter(self):
         print("""
         You are met with some strange things.
         This is a locked room.
         It will be a good idea to leave right away.
         You see a Gothon blocking the door.
         Try to do something.
         """)
         action = input('>')
         if action == 'shoot!':
             return 'death'
         elif action == 'tell a joke!':
             return 'laser_weapon_armory'
         else:
             print("Nothing happened.")
             return 'central_corridor'

 class LaserWeaponArmory(Scene):

     def enter(self):
         print("""
         This is the laser weapon armory.
         Destroy their weapon!
         Please enter the code.
         """)

         code = ""
         guess = input('>')
         guesses = 0

         while guess != code and guesses < 5:
             print("That's not right!")
             guesses += 1
             guess = input('Try again >')

         if guess == code:
             print("Bingo! The weapon is destroyed!")
             return 'the_bridge'
         else:
             print("A bell rings and you are locked here to die!")
             return 'death'

 class TheBridge(Scene):

     def enter(self):
         print("A bridge is in front of you and you see a huge bomb. ")
         action = input('>')

         if action == "throw it away":
             print("It exploded as you aprroached it. You died.")
             return 'death'
         elif action == "leave it behind":
             print("It seems nothing happened. You can safely pass it.")
             return 'escape_pod'
         else:
             return 'death'

 class EscapeRod(Scene):

     def enter(self):
         print("""
         You finally make it to the escape rod.
         There are five ships in front of you.
         Which one do you want to take?
         """)
         num = input('>')
         correct_ship = ''
         if num == correct_ship:
             print("You got on the ship. Everything seems getting on well. You won!")
             return 'finished'
         else:
             print("The ship is not working well. It exploded as take off!. You died!")
             return 'death'

 class Finished(Scene):

     def enter(self):
         print("Congratulations! You successfully escaped from the ship!")
         return 'finished'

 # 定义了各场景的名字，定义了进出场景的方法
 class Map(object):

     scenes = {'central_corridor': CentralCorridor(),
               'laser_weapon_armory': LaserWeaponArmory(),
               'the_bridge': TheBridge(),
               'escape_pod': EscapeRod(),
               'death': Death(),
               'finished': Finished()
               }

     def __init__(self, start_scene):
         self.start_scene = start_scene

     def next_scene(self, scene_name):
         nextScene = Map.scenes.get(scene_name)
         return nextScene                            # 根据传入名称返回一个场景的类

     def opening_scene(self):
         return self.next_scene(self.start_scene)    # 根据出发点名称返回出发点场景的类

 a_map = Map("central_corridor")
 a_game = Engine(a_map)
 a_game.play()