学习日记0827异常处理 元类 自定义元类 自定义元类来实例化类 属性查找顺序

try:
    #要处理的可能含有异常的语句
Except 异常类型 as 变量名(里面存放的是要抛出的异常的信息):
    #抛出异常是处理的代码

class OldboyTeacher:
    def __init__(self,name,age,sex):
        self.name=name
        self.age=age
        self.sex=sex

    def score(self):
        print(‘%s is scoring‘ %self.name)

tea1=OldboyTeacher(‘egon‘,18,‘male‘)#对象tea1是OldboyTeacher实例化得来的,那么对象OldboyTeacher是元类type实例化得来的
# print(type(tea1))
print(type(OldboyTeacher))

class_name = ‘OldBoy‘
class_base = (object,)
class_dic = {}
class_body="""
school = ‘Oldboy‘

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

def score(self):
    print(‘%s is scoring‘ %self.name)
"""
exec(class_body,{},class_dic)
OldBoy = type(class_name,class_base,class_dic)

class Mymate(type):#凡是继承了type的类都叫元类
    def __init__(self,class_name,class_base,class_dic):
           if not class_name.lower():
                raise typeError(‘类型必须是驼峰体‘)

    doc=class_dic.get(‘__doc__‘)
        if doc is None or len(doc) == 0 or len(doc.strip(‘\n ‘)) == 0:
            raise TypeError(‘类体中必须有文档注释,且文档注释不能为空‘)

class OldboyTeacher(object,metaclass=Mymeta): #OldboyTeacher=Mymeta(‘OldboyTeacher‘,(object,),{...})
    school = ‘Oldboy‘

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

    def score(self):
        print(‘%s is scoring‘ %self.name)
print(OldboyTeacher.__dict__)

class Mymate(type):
    def __call__(self,*args,**kwargs):
        obj = self.__new__(self)
        obj.__init__(obj,*args,**kwargs)
        return obj
class OldboyTeacher(object,metaclass=Mymeta): 
    school = ‘Oldboy‘

    def __init__(self,name,age,sex):
        self.name=name
        self.age=age
        self.sex=sex
    def score(self):
        print(‘%s is scoring‘ %self.name)

tea1=OldboyTeacher(‘egon‘,18,‘male‘) # 会触发OldboyTeacher的类(即元类)中的    __call__函数
tea1()