# -*- coding: utf-8 -*-"""Created on Tue Mar 19 21:40:15 2019@author: fengs""""""测试题：0. 请问以下代码的作用是什么？这样写正确吗？（如果不正确，请改正）def __setattr__(self, name, value):        self.name = value + 1        在设置时被调用,但写得不正确,应该用映射/键值对的写法赋值 self.__dict__[name] = value + 11.自定义该类的属性被访问的行为，你应该重写哪个魔法方法？    __getattribute__(self,name)    2. 在不上机验证的情况下，你能推断以下代码分别会显示什么吗？3. 在不上机验证的情况下，你能推断以下代码分别会显示什么吗？4. 请指出以下代码的问题所在：        """#测试题0class Test(object):        def __setattr__(self,name,value):        self.__dict__[name] = value + 1        #print(name)        #self.name = value + 1        #test = Test()#test.x = 1#print(test.x)#测试题2class C:    def __getattr__(self, name):        print('-----')        print(1)        print('-----')    def __getattribute__(self, name):        print('-----')        print(2)        print('-----')    def __setattr__(self, name, value):        print('-----')        print(3)        print('-----')    def __delattr__(self, name):        print('-----')        print(4)        print('-----')                #c = C()#c.x = 1# 位置一，请问这里会显示什么？-------->   3#print(c.x)# 位置二，请问这里会显示什么？-------> 2 None#测试题3class C3:    def __getattr__(self, name):        print(1)        return super().__getattr__(name)    def __getattribute__(self, name):        #print(2)        print(name)        return super().__getattribute__(name)    def __setattr__(self, name, value):        print(3)        super().__setattr__(name, value)    def __delattr__(self, name):        print(4)        super().__delattr__(name)                c3 = C3() #在__init__和 __new__时,其实__getattribute__就会被调用很多次了#c3.x#--------------------->  __getattr__ 并不存在, object没有 __getattr__这个魔方函数class Counter:    def __init__(self):        self.counter = 0    def __setattr__(self, name, value):               print(name)        print(value)        super().__setattr__(name, value)        #self.counter += 1    def __delattr__(self, name):        self.counter -= 1        print(self.counter)        super().__delattr__(name)#count = Counter()#del count.counter#self.counter = 0时会触发__setattr__,而+1操作要求counter已经定义才行,若在__setattr__中对counter进行操作，会引发递归调用"""动动手00. 按要求重写魔法方法：当访问一个不存在的属性时，不报错且提示“该属性不存在！”"""class dds0(object):            #如果访问的属性存在，就不会调用__getattr__方法 可以直接改写成 return "该属性不存在"    def __getattr__(self,name):        if name not in self.__dict__:            print("该属性不存在!")            return None        else:            return super().__getattribute__(self,name)#d = dds0()#d.y = 10#print(d.y)#d.x"""1. 编写 Demo 类，使得下边代码可以正常执行>>> demo = Demo()>>> demo.x'FishC'>>> demo.x = "X-man">>> demo.x'X-man'"""#我的写法class Demo():    def __init__(self):        self.x = 'Fishc'        #小甲鱼的写法class Demo2:    def __getattr__(self, name):        self.name = 'FishC'        return self.namedemo = Demo2()print(demo.x)demo.x = "X-man"print(demo.x)#小甲鱼的写法也可以,第一次打印demo.x时,x不存在所以会调用 __getattr__,第二次打印已经有x了不会调用 __getattr__了    #demo = Demo()#print(demo.x)#demo.x = "X-man"#print(demo.x)"""2. 修改上边【测试题】第 4 题，使之可以正常运行：编写一个 Counter 类，用于实时检测对象有多少个属性"""class dds2():    def __init__(self):        self.counter = 0    def __getattribute__(self,name):        if name == 'counter':            self.__dict__[name] = len(self.__dict__) - 1        return super().__getattribute__(name)            #d = dds2()#d.x = 1#d.y = 1#print(d.counter)#del d.x#print(d.counter)#del d.y #print(d.counter)