面向对象的封装2

class Foo:
    def __func(self): #私有属性在定义阶段就发生变化，_Foo__func
        print(‘Foo‘)
class  Bar(Foo):
    def __func(self): #因为在定义阶段就发生了变化，所以子类不能继承父类的私有属性
        print(‘Bar‘)


b = Bar()
b._Foo__func()
b._Bar__func()

class A:
    def foo(self):
        print(‘A.foo‘)
        self.__bar() #调用私有方法，找不到，除了自己类以外的方法

    def __bar(self):
        print(‘A.bar‘)
class B(A):
    def __bar(self):
        print(‘B.bar‘)

b = B()
b.foo()


class Teacher():
    def __init__(self,username,password):
        if not isinstance(password,str):
            raise Exception(‘密码只能是字符串‘)
        self.__uname = username
        self.__pwd = password
    @property
    def name(self):
        return self.__uname
    @name.setter
    def name(self,val):
        print(type(val))
        if not isinstance(val,str):
            raise TypeError(‘must be str‘)
        self.__uname=val
    @name.deleter
    def name(self):
        import re
        if re.findall(‘(?i)sb‘,self.__uname): #(?i) 不区分大小写
            raise PermissionError(‘SB not Deleting permissions‘)
        else:
            del self.__uname

egon = Teacher(‘egon‘,‘123‘)
egon.name = (‘egonSB‘)
print(egon.name)

del egon.name