代碼如下:

>>>def A():  
return A()  
>>>A() #無限循環(huán)，等消耗掉所有內(nèi)存資源后，報最大遞歸深度的錯誤    
File "<pyshell#2>", line 2, in A return A()RuntimeError: maximum recursion depth exceeded  
class Bird:  
    def __init__(self):  
        self.hungry = True  
    def eat(self):  
        if self.hungry:  
            print "Ahaha..."  
            self.hungry = False  
        else:  
            print "No, Thanks!"  

該類定義鳥的基本功能吃，吃飽了就不再吃

輸出結(jié)果:

代碼如下:

>>> b = Bird()  
>>> b.eat()  
Ahaha...  
>>> b.eat()  
No, Thanks!  

下面一個子類SingBird,

代碼如下:

class SingBird(Bird):  
    def __init__(self):  
        self.sound = 'squawk'  
    def sing(self):  
        print self.sound 

輸出結(jié)果:

代碼如下:

>>> s = SingBird()  
>>> s.sing()  
squawk  

SingBird是Bird的子類，但如果調(diào)用Bird類的eat()方法時,

代碼如下:

>>> s.eat()  
Traceback (most recent call last):  
  File "<pyshell#5>", line 1, in <module>  
    s.eat()  
  File "D:\Learn\Python\Person.py", line 42, in eat  
    if self.hungry:  
AttributeError: SingBird instance has no attribute 'hungry'  

【錯誤分析】代碼錯誤很清晰,SingBird中初始化代碼被重寫，但沒有任何初始化hungry的代碼

代碼如下:

class SingBird(Bird):  
    def __init__(self):  
        self.sound = 'squawk'  
        self.hungry = Ture #加這么一句  
    def sing(self):  
        print self.sound