关于类和属性python

Question

我正在研究一个教程，其中它在python上创建了一个基于文本的游戏，以练习使用类和属性。

基本结构是Scene将是超类，引擎将运行以进入下一个场景。

我在理解命令的后三行如何工作时遇到了麻烦。

据我了解。

a_map = Map('central_corridor')创建该类的一个实例Map它运行__init__在功能Map从而打印start_scene in __init__ central corridor 。

然后a_game = Engine(a_map)创建的实例Engine并运行__init__的Engine从而打印Engine __init__ has scene map, scene_map

现在我不明白要打印的最后一部分

start_scene in opening_scene
start_scene in next_scene
next_scene returns _____

然后它运行a_game.play()

如果您能解释一下两者之间发生的事情，那将是很好的。

from sys import exit
from random import randint

class Scene(object):
    def enter(self):
        pass 


class Engine(object):
    def __init__(self, scene_map):
        print "Engine __init__ has scene map", scene_map
        self.scene_map = scene_map`

    def play(self):
        current_scene = self.scene_map.opening_scene()
        print "Plays first scene", current_scene

        while True:
            print "\n------------"
            next_scene_name = current_scene.enter()
            print "next scene", next_scene_name
            current_scene = self.scene_map.next_scene(next_scene_name)

class CentralCorridor(Scene):
    pass

class LaserWeaponArmory(Scene):
    pass

class Bridge(Scene):
    pass

class EscapePod(Scene):
     pass

class Death(Scene):
    pass

class Map(object):        
    scenes = {
        'central_corridor' : CentralCorridor(),
        'laserweaponarmory' : LaserWeaponArmory(),
        'Bridge' : Bridge(),
        'escape_pod' : EscapePod(),
        'Death' : Death()
    }
    def __init__(self, start_scene):
        self.start_scene = start_scene
        print "start_scene in __init__", self.start_scene

    def next_scene(self, scene_name):
        print "start_scene in next_scene"
        val = Map.scenes.get(scene_name)
        print "next_scene returns", val
        return val

    def opening_scene(self):
        print "start_scene in opening_scene"
        return self.next_scene(self.start_scene)

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

Answer 1

澄清：

start_scene in opening_scene
start_scene in next_scene
next_scene returns _____

并且由于运行

a_game.play()

引擎和地图如下所示：

Engine
- scene_map <- Scene
- start_scene <- String
+ __init__()
+ next_scene()
+ opening_scene()


Map
- start_scene <- String
- scenes <- Dictionary of Scene
+ __init__()
+ play()

---

play（）在scene_map上调用opening_scene（）：

self.scene_map.opening_scene()

opening_scene（）使用“ central_corridor”调用next_scene（）

self.next_scene(self.start_scene)

next_scene（）使用传入的键“ central_corridor”在场景字典中查找相关场景。

Map.scenes.get(scene_name)

通过方法调用链返回场景，并将其存储在current_scene中

current_scene = self.scene_map.opening_scene()