题目：模拟游戏奥特曼打小怪兽

代码如下：

# 模拟一个游戏，有一个怪兽（Monster），还有一个玩家（hero）。
import random as rn
class Sprite:
    def __init__(self, name):
        self.blood = 100
        self.power = 12
        self.name = name

    def attack(self, monster):
        minus = rn.randint(self.power - 5, self.power + 5)
        if monster.has_living():
            monster.minus_blood(minus)
        print(monster.name + ":" + str(monster.blood))

    def minus_blood(self, num):
        self.blood -= num

    def has_living(self):
        if self.blood > 0:
            return True
        return False

m = Sprite('哥斯拉')
h = Sprite('奥特曼')

while m.has_living() and h.has_living():
    m.attack(h)
    h.attack(m)

if m.has_living():
    print(m.name + '获得胜利')
if h.has_living():
    print(h.name + '获得胜利')

用面向对象思路解决前面用函数解决的登录注册问题

# 用面向对象的思维完成一个注册登录系统
class User:
    """一个用户类"""
    def __init__(self, username, pwd):
        self.username = username
        self.pwd = pwd

    def __str__(self):
        return self.username
class DB:
    """
    单例模式
    """
    instance = None

    def __new__(cls, *args, **kwargs):
        """为了实现单例"""
        if DB.instance is None:
            DB.instance = super().__new__(cls)

        return DB.instance

    def __init__(self):
        self._pool = []

    def sava_user(self, user):
        """
        存储数据
        :return:
        """
        self._pool.append(user)

    def get_user_by_username(self, username):
        """
        查找数据
        :param username:用户名
        :return:
        """
        for user in self._pool:
            if username == user.username:
                return user
        return None

    def get_all(self):
        return self._pool[:]

class View:
    """
    读取用户信息
    """
    def show_info(self, info):
        opt = input(info)
        return opt

    def read_regiseter_info(self):
        username = input('请输入用户名（长度6-9）：\n')
        if 6 > len(username) or len(username) > 9:
            print('用户名不合法！')
            return None

        pwd = input('请输入密码（长度6-9）：\n')
        if 6 > len(pwd) or len(pwd) > 9:
            print('密码不合法！')
            return None
        return User(username, pwd)

    def show_user_list(self, users):
        """
        展示用户信息
        :param users:
        :return:
        """
        for user in users:
            print(user)

class Service:
    def __init__(self):
        self.db = DB()

    def regiser(self, user):
        exist_user = self.db.get_user_by_username(user.username)
        if exist_user is not None:
            return print("该用户已存在")

        self.db.sava_user(user)
        print('用户注册成功')

    def login(self, user):
        exist_user = self.db.get_user_by_username(user.username)
        if exist_user is None:
            print('用户名不存在')
            return None

        if exist_user.pwd == user.pwd:
            print("登录成功\n")
            return exist_user

        else:
            print("密码错误")
            return None

    def list(self):
        return self.db.get_all()


class App:
    def __init__(self):
        self.v = View()
        self.s = Service()
        self.cur_user = None

    def start(self):
        while True:
            view_opt = self.v.show_info(" (1)注册 \n (2)登录 \n (3) 退出 \n 请选择要进行的操作:")
            if view_opt == '1':
                user = self.v.read_regiseter_info()
                if user is not None:
                    self.s.regiser(user)

            if view_opt == '2':
                user = self.v.read_regiseter_info()
                login_user = self.s.login(user)
                if login_user is not None:
                    self.cur_user = login_user
                    self.show_home()

    def show_home(self):
        while True:
            user_opt = self.v.show_info("请选择要进行的操作：\n (1)查看用户信息 \n (2)查看用户列表 \n (3) 退出")
            if user_opt == '1':
                print(self.cur_user)

            if user_opt == '2':
                # 查看用户列表
                users = self.s.list()
                print(type(users))
                self.v.show_user_list(users)
                

            if user_opt == '3':
                break

app = App()
app.start()

实现一个监控程序

## 模拟监控服务：观察者模式
## 程序，每隔5秒向服务器发送请求，看是否获取正常返回，如果返回正常，则继续监控，否则向维护人员发送短信

import time
from random import randint

class Server:
    """
    服务器的功能是求两个数的和
    """
    def __init__(self, name):
        self.name = name
        self.times = randint(3,10)

    def action(self):
        self.times -= 1
        return self.times

class Monitor:
    def __init__(self, server):
        self.server = server

    def monitor(self):
        while True:
            s = self.server.action()
            if s < 3 or s > 10:
                print('向维护人员发送信息')
                break

            else:
                print('服务器正常，无需发送信息')
            time.sleep(5)

 while True:
     s = Server('test')
     m = Monitor(s)
     m.monitor()