class Person(object):
    """
    目的：让外界只可以读取，不能修改
    """

    def __init__(self):
        # 首先将属性设置为外界既不能读取也不能修改
        self.__age = 18

    # 然后提供方法让外界读取，只提供读方法，不提供写方法
    # @property装饰器的作用是让方法以属性的形式提供给外界调用
    @property
    def age(self):
        return self.__age


p = Person()
print(Person().age)
# 外界尝试修改age，则会报错
p.age = 10



/Users/jun/anaconda3/envs/python36/bin/python /Users/jun/PycharmProjects/pyqt5/面向对象/只读属性.py
18
Traceback (most recent call last):
  File "/Users/jun/PycharmProjects/pyqt5/面向对象/只读属性.py", line 19, in <module>
    p.age=10
AttributeError: can't set attribute

Process finished with exit code 1