@property 装饰器

property() 函数作用于新式类，返回属性值。

class C(object):
    def __init__(self):
        self._x = None

    def getx(self):
        print('get')
        return self._x

    def setx(self, value):
        print('set')
        self._x = value

    def delx(self):
        print('del')
        del self._x

    x = property(getx, setx, delx, "I'm the 'x' property.")


# c = C()
# c.x = 12
# print(c.x)
# del c.x

@property 装饰器用的最多。把一个方法变成属性调用，那么我们在对实例属性操作的时候，就知道该属性很可能不是直接暴露的，而是通过getter和setter方法来实现的。

# @property 装饰器负责把一个方法变成属性调用

class Student(object):
    # 把一个getter方法变成属性，只需加上 @property
    @property
    def score(self):
        return self._score

    # 把一个setter方法变成属性，@fun.setter
    @score.setter
    def score(self, value):
        if not isinstance(value, int):
            raise ValueError('score must be an interger!')
        if value < 0 or value > 100:
            raise  ValueError('score must between 0~100')
        self._score = value

s = Student()
s.score = 60
print(s.score)

class Parrot(object):
    def __init__(self):
        self._voltage = 100000

    @property
    def voltage(self):
        """Get the current voltage."""
        return self._voltage

    # setter,deleter，这些额外函数名和property相同
    @voltage.setter
    def voltage(self, value):
        self._voltage = value

    @voltage.deleter
    def voltage(self):
        del self._voltage

参考：
https://www.liaoxuefeng.com/wiki/0014316089557264a6b348958f449949df42a6d3a2e542c000/00143186781871161bc8d6497004764b398401a401d4cce000
http://www.runoob.com/python/python-func-property.html