高封装的property方法

class Person():
    def __init__(self):
        self.__age = 0

    def set_age(self, age):
        if age < 0 or age > 200:
            self.__age = 0
        else:
            self.__age = age

    def get_age(self):
        return self.__age

    a = property(get_age, set_age)

    # def __init__(self, fget=None, fset=None, fdel=None, doc=None):  # known special case of property.__init__
    """

    property(fget=None, fset=None, fdel=None, doc=None) -> property attribute

    fget is a function to be used for getting an attribute value, and likewise
    fset is a function for setting, and fdel a function for del'ing, an
    attribute.  Typical use is to define a managed attribute x:

    """

p = Person()
p.a = 999
print(p.a)