[已解决]第045讲课程问题请益

soonna

1. class R:
   
2.         def __init__(self):
   
3.                 self.counter = 0
   
4.         def __setattr__(self, name, value):
   
5.                 self.counter = value

复制代码

>>> r = R()
Traceback (most recent call last):
  File "<pyshell#38>", line 1, in <module>
    r = R()
  File "<pyshell#37>", line 3, in __init__
    self.counter = 0
  File "<pyshell#37>", line 5, in __setattr__
    self.counter = value
  File "<pyshell#37>", line 5, in __setattr__
    self.counter = value
  File "<pyshell#37>", line 5, in __setattr__
    self.counter = value
  [Previous line repeated 326 more times]
RecursionError: maximum recursion depth exceeded while calling a Python object

因self.counter = 0赋值操作触发__setattr__, 而其中self.counter = value又是赋值操作，所以造成死循环。

1. class R:
   
2.         def __init__(self):
   
3.                 self.counter = 0
   
4.         def __setattr__(self, name, value):
   
5.                 self.counter = self.counter + value

复制代码

>>> r = R()
Traceback (most recent call last):
  File "<pyshell#35>", line 1, in <module>
    r = R()
  File "<pyshell#34>", line 3, in __init__
    self.counter = 0
  File "<pyshell#34>", line 5, in __setattr__
    self.counter = self.counter + value
AttributeError: 'R' object has no attribute 'counter'

请问为什么程式码只有些改变，为什么却变成没有属性counter呢？真得想不懂？ ？ ？

最佳答案

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塔利班

2018-4-11 20:33:59

counter属性还没定义出去，先进行了赋值，赋值里对counter属性操作，当然没定义

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塔利班

counter属性还没定义出去，先进行了赋值，赋值里对counter属性操作，当然没定义