python: 面向对象高级编程@property用法（超容易理解）

要了解@property的用法，必选先知道在类里面变量的区别

一、变量访问

class People(object):
    def __init__(self, name, age, number):
        self.name = name
        self.age = age
        self.__number = number # 私有属性

首先定义一个People类，这里name和age是可以从外部被访问的，而number不行，number是私有变量。

>>> people = People(name='Tom', age=23, number=0)
>>> people.name
'Tom'
>>> people.age
23
>>> people.number
Traceback (most recent call last):
  File "", line 1, in <module>
    people.number
AttributeError: 'People' object has no attribute 'number'

二、@Property的作用

为了能够从外部访问，并操作私有变量，有了@Property这玩意。
1、访问
对上面代码进行修改

class People(object):
    def __init__(self, name, age, number):
        self.name = name
        self.age = age
        # 私有属性
        self.__number = number
  
    @property
    def number(self):
        return self.__number # 返回私有属性值

此时，私有变量number，可以被访问了。

>>> people = People(name='Tom', age=23, number=0)
>>> people.number
0

2、赋值
上面的代码，只能访问，不能赋值，再增加。

class People(object):
    def __init__(self, name, age, number):
        self.name = name
        self.age = age
        # 私有属性
        self.__number = number
   
    @property
    def number(self):
        return self.__number # 返回私有属性值

    @number.setter
    def number(self, value):
        self.__number = value  # 设置__number的值

此时，私有变量number可以被访问， 也可以被修改了！

>>> people = People(name='Tom', age=23, number=0)
>>> people.number
0
>>> people.number = 3
>>> people.number
3

3、删除
再增加一个功能删除

class People(object):
    def __init__(self, name, age, number):
        self.name = name
        self.age = age
        # 私有属性
        self.__number = number
   
    @property
    def number(self):
        return self.__number # 返回私有属性值

    @number.setter
    def number(self, value):
        self.__number = value  # 设置__number的值

    @number.deleter
    def number(self):
        del self.__number # 删除属性

此时number可以被访问，被修改，被删除

>>> people = People(name='Tom', age=23, number=0)
>>> people.number
0
>>> del people.number
>>> people.number
Traceback (most recent call last):
  File "", line 1, in <module>
    people.number
  File "C:\Users\Lenove\Desktop\tx.py", line 10, in number
    return self.__number # 返回私有属性值
AttributeError: 'People' object has no attribute '_People__number'

扫一下，谢。