知识点：类2

>>> class Person:
...     def __init__(self, name, age):
...             self.name = name
...             self.age = age
...
>>> tom = Person("Tom", 35)
>>> dir(tom)
[‘__doc__‘, ‘__init__‘, ‘__module__‘, ‘age‘, ‘name‘]
>>> delattr(tom, "age")
>>> dir(tom)
[‘__doc__‘, ‘__init__‘, ‘__module__‘, ‘name‘]

class C:
    def __init__(self , size=10):
        self.size = size

    def getSize(self):
        return self.size

    def setSize(self , value):
        self.size = value

    def delSize(self):
        del self.size

    x = property(getSize , setSize , delSize)


c1 = C()
c.getSize()  #>>> 10
c1.x         #>>> 10
c1.x=18
c1.x         #>>> 18
c.getSize()  #>>> 18
del c1.x
c1.size      #AttributeError: ‘C‘ object has no attribute ‘size‘