python 类属性和实例属性、方法 访问权限问题

class Animal:
    cls_attr = 'cls_attr'
    _cls_attr = '_cls_attr'
    __cls_attr = '__cls_attr'

    def __init__(self):
        self.ins_attr = 'ins_attr'
        self._ins_attr = '_ins_attr'
        self.__ins_attr = '__ins_attr'
        print('Animal __init__')

    def func(self):
        print('func')

    def _func(self):
        print('_func')

    def __func(self):
        print('__func')

    def __del__(self):
        print('Animal __del__')


class Dog(Animal):

    def __init__(self):
        '''子类重写__init__函数时，需手动调用父类的__init__函数'''
        print('Dog __init__')
        super(Dog, self).__init__()

    def __del__(self):
        print('Dog __del__')
        super(Dog, self).__del__()


a = Animal()
print(a.cls_attr)
print(a._cls_attr)
# print(a.__cls_attr)
print(a._Animal__cls_attr)
print(a.ins_attr)
print(a._ins_attr)
# print(a.__ins_attr)
print(a._Animal__ins_attr)
a.func()
a._func()
# a.__func()
a._Animal__func()
del a

print('-' * 50)

d = Dog()
print(d.cls_attr)
print(d._cls_attr)
# print(d.__cls_attr)
print(d._Animal__cls_attr)
print(d.ins_attr)
print(d._ins_attr)
# print(d.__ins_attr)
print(d._Animal__ins_attr)
d.func()
d._func()
# a.__func()
d._Animal__func()
del d

Animal __init__
cls_attr
_cls_attr
__cls_attr
ins_attr
_ins_attr
__ins_attr
func
_func
__func
Animal __del__
--------------------------------------------------
Dog __init__
Animal __init__
cls_attr
_cls_attr
__cls_attr
ins_attr
_ins_attr
__ins_attr
func
_func
__func
Dog __del__
Animal __del__