從Python 2.7中的另一個類方法調用一個類方法

Question

我很困惑為什么這段代碼行不通。 對於room_instance = self.startRoom()我得到了錯誤：

'str' object is not callable.  

我的代碼：

class Corridor:
    def enter(self):
        print "Yureka. First Room!"

class Engine(object):
    def __init__(self, startRoom):
        self.startRoom = startRoom   #sets the startRoom to 'Corridor' for the eng instance
    def room_change(self):
        room_instance = self.startRoom()
        room_instance.enter()

eng = Engine('Corridor')
eng.room_change()

Answer 1

當您使用eng = Engine('Corridor') ，會將'Corridor'作為字符串傳遞。 要訪問類走廊，您應該使用globals()['Corridor']

class Engine(object):
    def __init__(self, startRoom):
        self.startRoom = globals()[startRoom]   #sets the startRoom to 'Corridor' for the eng instance

    def room_change(self):
        room_instance = self.startRoom()
        room_instance.enter()

但這實際上是一個相當脆弱的構造，因為可能在其他模塊等中定義了Corridor 。因此，我提出以下建議：

class Corridor:
    def enter(self):
        print "Yureka. First Room!"

class Engine(object):
    def __init__(self, startRoom):
        self.startRoom = startRoom   #sets the startRoom to 'Corridor' for the eng instance
    def room_change(self):
        room_instance = self.startRoom()
        room_instance.enter()

eng = Engine(Corridor) # Here you refer to _class_ Corridor and may refer to any class in any module
eng.room_change()