python使用map来模拟switch

使用python中的字典来模拟其他语言中的case,switch 语句。
使用函数作为字典的value. 看代码很直观。
该代码出自The Python Master一书.

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1. def labyrinth(position, alive):
   
2.     print('You are in a maze of twisty passages, all alike.')
   
3.     return position, alive
   
4. 
   
5. def dark_forest_road(position, alive):
   
6.     print("You are on a road in a dark forest. To"
   
7.     " The north you can see a tower.")
   
8.     return position, alive
   
9.     
   
10. def tall_tower(position, alive):
    
11.     print("There is a tall tower here, with no obvious door. "
    
12.     "A path leads east.")
    
13.     return position, alive
    
14. 
    
15. def rabbit_hole(position, alive):
    
16.     print("You fall down a rabbit hole into a labyrinth.")
    
17.     return (0,0), alive
    
18. 
    
19. def lava_pit(position, alive):
    
20.     print("You fall into a lava pit.")
    
21.     return position, False
    
22. 
    
23. def go_north(position):
    
24.     i, j = position
    
25.     new_position = (i, j + 1)
    
26.     return new_position
    
27. 
    
28. def go_east(position):
    
29.     i, j = position
    
30.     new_position = (i + 1, j)
    
31.     return new_position
    
32. 
    
33. def go_south(position):
    
34.     i, j = position
    
35.     new_position = (i, j - 1)
    
36.     return new_position
    
37. 
    
38. def go_west(position):
    
39.     i, j = position
    
40.     new_position = (i - 1, j)
    
41.     return new_position
    
42. 
    
43. def look(position):
    
44.     return position
    
45. 
    
46. def quit(position):
    
47.     return None
    
48. 
    
49. locations = {
    
50.     (0, 0): labyrinth,
    
51.     (1, 0): dark_forest_road,
    
52.     (1, 1): tall_tower,
    
53.     (2, 1): rabbit_hole,
    
54.     (1, 2): lava_pit,
    
55.     }
    
56.     
    
57. actions = {
    
58.     'N': go_north,
    
59.     'E': go_east,
    
60.     'S': go_south,
    
61.     'W': go_west,
    
62.     'L': look,
    
63.     'Q': quit,
    
64.     }
    
65. 
    
66. 
    
67. 
    
68. def play():
    
69.     
    
70.     position = (0, 0)
    
71.     alive = True
    
72.     
    
73.     while position:
    
74.         
    
75.         try:
    
76.             location_action = locations[position]
    
77.         except KeyError:
    
78.             print("There is nothing here.")
    
79.         else:
    
80.             position, alive = location_action(position, alive)
    
81.             if not alive:
    
82.                 print("You're dead")
    
83.                 break
    
84.         
    
85.         command = input()
    
86.         
    
87.         try:
    
88.             command_action = actions[command]
    
89.         except KeyError:
    
90.             print("I don't understand")
    
91.         else:
    
92.             position = command_action(position)
    
93.         
    
94. 
    
95.     else: #nobreak
    
96.         print("You have chosen to leave the game")
    
97.     
    
98.     print("Game Over")
    
99.     
    
100. play()

执行起来结果如下：

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1. root@kali:/usr/local/src/py/project_dirs# ./emulate_switch_3.py
   You are in a maze of twisty passages, all alike.
   E
   You are on a road in a dark forest. To The north you can see a tower.
   N
   There is a tall tower here, with no obvious door. A path leads east.
   N
   You fall into a lava pit.
   You're dead
   Game Over
   root@kali:/usr/local/src/py/project_dirs# ./emulate_switch_3.py
   You are in a maze of twisty passages, all alike.
   E
   You are on a road in a dark forest. To The north you can see a tower.
   N
   There is a tall tower here, with no obvious door. A path leads east.
   E
   You fall down a rabbit hole into a labyrinth.
   E
   You are on a road in a dark forest. To The north you can see a tower.
   N
   There is a tall tower here, with no obvious door. A path leads east.
   E
   You fall down a rabbit hole into a labyrinth.
   Q
   You have chosen to leave the game
   Game Over