class Base:
? ? def __init__(self, value):
? ? ? ? self.__value = value
?
b = Base(5)
print(assert b.__value)
?
Traceback (most recent call last):
? File "/Users/yangjiajia/Desktop/project/python/algebra/test.py", line 19, in <module>
? ? print(b.__value)
AttributeError: 'Base' object has no attribute '__value'

class Parent:
? ? def __init__(self, value):
? ? ? ? self.__value = value?
?
class Child(Parent):
? ? def get_value(self):
? ? ? ? return self.__value
?
child = Child(4)
print(child.get_value())
?
Traceback (most recent call last):
? File "/Users/yangjiajia/Desktop/project/python/algebra/test.py", line 24, in <module>
? ? print(child.get_value())
? File "/Users/yangjiajia/Desktop/project/python/algebra/test.py", line 21, in get_value
? ? return self.__value
AttributeError: 'Child' object has no attribute '_Child__value'

class Parent:
? ? def __init__(self, value):
? ? ? ? self.__value = value?
?
class Child(Parent):
? ? def name(self):
? ? ? ? names = 'yang'
?
? ? def get_value(self):
? ? ? ? return self.__value
?
child = Child(4)
print(child.__dict__)
?
{'_Parent__value': 4}

class Parent:
? ? def __init__(self, value):
? ? ? ? self._value = value?
?
class Child(Parent):
? ? def get_value(self):
? ? ? ? return self._value
?
child = Child(4)
assert child._value == 4

class Dog(object):
? ? __slots__ = ('__name', 'kind', 'level')
? ? def __init__(self,name,kind,level):#構(gòu)造函數(shù)，定義屬性和初始方法
? ? ? ? self.__name=name
? ? ? ? self.kind=kind
? ? ? ? self.level=level#賦值
? ? ? ? print(f"This is a {self.kind} dog called {self.__name} with level {self.level}")
?
? ? def run(self):#定義類中的方法
? ? ? ? print(f"{self.__name} is now running!")
?
? ? def roll_over(self):
? ? ? ? print(f"{self.__name} is now rolling over!")
?
? ? def change_level(self):
? ? ? ? self.level+=1#修改類中屬性的值
? ? ? ? print(f"The level of {self.__name} is now {self.level}")

from Zoo.Dog import Dog#導(dǎo)包
?
dog=Dog("Halo","Husty",3)#實(shí)例化
?
dog.run()
dog.roll_over()
dog.change_level()#調(diào)用方法

print(dog.__name)