Do

read it below

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#!/usr/bin/env python3
# -*- coding: utf-8 -*-
# @Date    : 2018-07-18 10:21:16
# @Author  : Simon (simon.xie@codewalker.meg)
# @Link    : http://www.codewalker.me
# @Version : 1.0.0

class Desc(object):
    def __init__(self, data):
        print(f'in init, data is: {data}')
        self.data = data
    def __get__(self, instance, owner):
        print('in get func')
        return self.data
    def __set__(self, instance, value):
        print(f'in set, value is {value}')
        self.value = value
class E(object):
    x = Desc(10)
    def __init__(self, data):
        self.x = data
e = E(5)
print(e.x)

Try to comment func __set__, then think about what&why the result are different.

Get

It’s become a non-data descriptor when func __set__ is commented.