自定义元类控制类的创建

# Chinese = Mymeta(class_name,class_bases,class_dic)
# 创建元类如下：


class Mymeta(type):
    def __init__(self, class_name, class_bases, class_dic):
        # print(class_name)
        # print(class_bases)
        # print(class_dic)
        # 打印结果如下：
        '''
        Chinese
        (<class 'object'>,)
        {'__module__': '__main__', '__qualname__': 'Chinese',
         'country': 'china', '__init__': <function Chinese.__init__ at 0x0000019CC0750AE8>,
          'talk': <function Chinese.talk at 0x0000019CC0750B70>}
          '''

        super(Mymeta, self).__init__(class_name, class_bases, class_dic)


class Chinese(object, metaclass=Mymeta):      # metaclass 元类
    country = 'china'

    def __init__(self, name, age):
        self.name = name
        self.age = age

    def talk(self):
        print('%s is talking' % self.name)


# ------------例子控制类----------------------------------------


class Mymeta(type):
    def __init__(self, class_name, class_bases, class_dic):
        if not class_name.istitle():                        # class_name 首字母不是大写就报类型错误
            raise TypeError('类型错误')
        if '__doc__' not in class_dic or not class_dic['__doc__'].strip():
            raise TypeError('必需要有注释且不能为空')

        super(Mymeta, self).__init__(class_name, class_bases, class_dic)


class Chinese(object, metaclass=Mymeta):      # metaclass 元类
    """
    这是中国人的类
    """
    country = 'china'

    def __init__(self, name, age):
        self.name = name
        self.age = age

    def talk(self):
        print('%s is talking' % self.name)