code_refactoring

# -*- coding:utf-8 -*-

import json
def get_stored_username():
    '''如果存储了用户名，就从文件获取用户名'''
    # filename = 'username.json'
    try:
        with open(filename) as file_read:
            username = json.load(file_read)
    except FileNotFoundError:
        return None
    else:
        return username

def get_new_username():
    '''提示用户输入用户名'''
    username = input("What is your name?")
    # filename = 'username.json'
    with open(filename, 'w') as file_obj:
        json.dump(username, file_obj)
    return username

def greet_user():
    '''问候用户并指出其姓名'''
    username = get_stored_username()
    if username:
        print("Welcome back, " + username + " !")
    else:
        username = get_new_username()
        print("We'll remember you when you come back, " + username + "!")

filename = 'username.json'
greet_user()