目录

• 第十三章、元类之控制类的调用过程
  • 一、__call__

第十三章、元类之控制类的调用过程

一、__call__

作用：控制类的调用过程,实际上在控制:对象的产生

• 控制名称空间

   class Mymeta(type):
        def __call__(self,*args, **kwargs):
            obj=self.__new__(self)#生成空对象
            obj.__init__(*args, **kwargs)#调用obj的__init__()
            obj.__dict__['attr']=kwargs
            return obj
  
    class Mydict(dict,metaclass=Mymeta):
        def __getattr__(self, item):
            return self.__dict__['attr'][item]
  
        def __setattr__(self, key, value):
            self[key]=value
            self.__dict__['attr'][key] = value
    ----------------------------------------------------
    di=Mydict(name='nick',age=18)
    print(di.__dict__)
    print(di.name)
    di.sex='male'
    print(di)
    print(di.__dict__)
    -----------------------------------------------------
    {'attr': {'name': 'nick', 'age': 18}}
    nick
    {'name': 'nick', 'age': 18, 'sex': 'male'}
    {'attr': {'name': 'nick', 'age': 18, 'sex': 'male'}}

• 例2练习:给我吧对象中的所有属性都设置成私有的

  class Mymeta(type):
      def __call__(self, *args, **kwargs):
          obj=object.__new__(self)
          obj.__init__(*args, **kwargs)
          # print(obj.__dict__)
          obj.__dict__={ '_%s__%s'%(self.__name__,k):v for k,v in obj.__dict__.items()}
          # print(obj.__dict__)
          return obj
  
  class Person(object, metaclass=Mymeta):
      school = 'oldboy'
      def __init__(self, name):
          self.name = name
      def score(self):
          print('分数是100')
  p = Person(name='nick')
  print(p.__dict__) #{'_Person__name': 'nick'}
  print(p.name)     #会报错

原文地址：https://www.cnblogs.com/demiao/p/11456347.html