问一个问题，有关__setattr__

验证执行结果：
>>> c = C()
Got it!
>>> c.__dict__
{'val': 10}
>>> c.ss
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
AttributeError: 'C' object has no attribute 'ss'
>>> c.ss = 2
Got it!
>>> c.__dict__
{'ss': 12, 'val': 10}
>>> c.me = 5
Got it!
>>> c.me
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
AttributeError: 'C' object has no attribute 'me'
>>> c.__dict__
{'ss': 12, 'val': 15}
>>> c.ss = 7
Got it!
>>> c.ss
17
>>> c.__dict__
{'ss': 17, 'val': 15}
>>> c.me = 90
Got it!
>>> c.__dict__
{'ss': 17, 'val': 100}

你这个问题 请先看英文
object.__setattr__(self, name, value)
Called when an attribute assignment is attempted. This is called instead of thenormal mechanism (i.e. store the value in the instance dictionary). name isthe attribute name, value is the value to be assigned to it.
If __setattr__() wants to assign to an instance attribute, it should notsimply execute self.name = value — this would cause a recursive call toitself. Instead, it should insert the value in the dictionary of instanceattributes, e.g., self.__dict__[name] = value. For new-style classes,rather than accessing the instance dictionary, it should call the base classmethod with the same name, for example, object.__setattr__(self, name,value).
在类中你显示定义了__setattr__ 这个方法，如果在方法内部
还通过这样self.name = value 会造成再次调用__setattr__ 这个方法,造成递归下去。
所以不能这样写代码
需要这样写 self.__dict__[name] = value.