代码重构

重构前：

import json

def greet_user():

    """问候用户，并指出其名字"""

    filename = "username.json"

    try:

        with open(filename) as file_obj:

            username = json.load(file_obj)

    except Exception as e:

        username = input("what is your name?")

        with open(filename, 'w') as file_obj:

            json.dump(username, file_obj)

            print("we'll remember you when you come back,"+username)

    else:

        print("welcome back," + username)

greet_user()

第一次重构：

def get_stored_username():

    """如果存储了用户名，就获取它"""

    try:

        filename = "username.json"

        with open(filename,'r') as file_obj:

            username = json.load(file_obj)

        except FileNotFoundError as fnf:

            return None

        else:

            return username

def greet_user():

    """问候用户，并指出其名字"""

    username = get_stored_username()

    if username:

        print("welcome back," + username)

    else:

    username = input("what is your name?")

    with open(filename, 'w') as file_obj:

        json.dump(username, file_obj)

        print("we'll remember you when you come back,"+username)

greet_user()

第二次重构：

import json

def get_stored_username():

    """如果存储了用户名，就获取它"""

    try:

        filename = "username.json"

        with open(filename,'r') as file_obj:

            username = json.load(file_obj)

    except FileNotFoundError as fnf:

        return None

    else:

        return username

def get_new_username()

    """获取新用户"""

    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，并指出其名字"""

    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)

greet_user()