关于零基础python45讲课后习题第二题方法
在小甲鱼的例程代码中我发现它有个不人性化的地方del一个本身就没有存在的属性时会出现错误：
>>> del a.b
Traceback (most recent call last):
File "<pyshell#256>", line 1, in <module>
del a.b
File "D:\学习\python\自编\小甲鱼\编写一个 Counter 类，用于实时检测对象有多少个属性.py", line 42, in __delattr__
super().__delattr__(name)
AttributeError: b
当我把counter删除掉的时候，我觉得不应该可以删除counter：
>>> del a.counter
>>> a.counter
Traceback (most recent call last):
File "<pyshell#258>", line 1, in <module>
a.counter
AttributeError: 'Counter' object has no attribute 'counter'
所以我就改了改代码：
class Counter:
def __init__(self):
super().__setattr__("counter",0)
def __getattribute__(self,name):
#print("找到该属性啦!")
try:
return super().__getattribute__(name)
except AttributeError as reason:
print("没有这个属性!")
#def __getattr__(self,name):
#if hasattr(self,name) == False:
#print("该属性不存在!")
#return False
def __setattr__(self,name,value):
if name != "counter":
super().__setattr__(name,value)
super().__setattr__("counter",self.counter+1)
#elif name == "counter":
#super().__setattr__("counter",0)
def __delattr__(self,name):
#print("delattr")
try:
if name != "counter" and hasattr(self,name) == True:
super().__delattr__(name)
super().__setattr__("counter",self.counter-1)
except AttributeError as reason:
print("没有这个属性!")
不过这样写感觉有点奇怪所以想请教大家有没有更好的办法谢谢啦 没人吗 if name != "counter" and hasattr(self, name) == True:
super().__delattr__(name)
super().__setattr__("counter", self.counter - 1)
这里可以简化，把 hasattr(self, name) == True 改为 hasattr(self, name) 也可以
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