python面向对象的约束和自定义异常

class BaseMessage(object):
    def send(self,x1):
        """
        必须继承BaseMessage，然后其中必须编写send方法。用于完成具体业务逻辑。
        """
        raise NotImplementedError(".send() 必须被重写.")

class Email(BaseMessage):
    def send(self,x1):
        """
        必须继承BaseMessage，然后其中必须编写send方法。用于完成具体业务逻辑。
        """
        print(‘发送邮件‘)

obj = Email()
obj.send(1)

from abc import ABCMeta,abstractmethod
class Base(metaclass=ABCMeta): # 抽象类
    def f1(self):
        print(123)
    @abstractmethod
    def f2(self):   # 抽象方法
        pass
class Foo(Base):
    def f2(self):
        print(666)
obj = Foo()
obj.f1()

class KeyError(Exception):
    pass

class MyException(Exception):
    def __init__(self,code,msg):
        self.code = code
        self.msg = msg
try:
    raise MyException(1000,‘操作异常‘)

except KeyError as obj:
    print(obj,1111)
except MyException as obj:
    print(obj.code,obj.msg)
except Exception as obj:
    print(obj,3333)