习题

习题

import uuid
import hwk_settings
import os
import pickle


class MySql:
    # 1.对象有id、host、port三个属性
    def __init__(self, host, port):
        self.id = self.create_id()
        self.host = host
        self.port = port

    # 2.定义工具create_id，在实例化时为每个对象随机生成id，保证id唯一
    def create_id(self):
        id = uuid.uuid1()
        return str(id)

    # 3.提供两种实例化方式，方式一：用户传入host和port 方式二：从配置文件中读取host和port进行实例化
    @classmethod
    def ince(cls):
        return cls(hwk_settings.HOST, hwk_settings.PORT)

    # 4.为对象定制方法，save和get_obj_by_id，save能自动将对象序列化到文件中，文件路径为配置文件中DB_PATH,文件名为id号，保存之前验证对象是否已经存在，若存在则抛出异常，;get_obj_by_id方法用来从文件中反序列化出对象
    def save(self):
        if self.exist():
            raise PermissionError('对象已存在')
        else:
            path = os.path.join(hwk_settings.PATH, self.id)
            pickle.dump(self, open(path, 'wb'))

    def exist(self):
        state = False

        if not os.path.exists(hwk_settings.PATH):
            os.mkdir(hwk_settings.PATH)
        files_name = os.listdir(hwk_settings.PATH)

        for file_name in files_name:
            file_path = r'%s%s%s' % (hwk_settings.PATH, os.sep, file_name)
            obj = pickle.load(open(file_path, 'rb'))
            if (obj.host == self.host) and (obj.port == self.port):
                state = True
                return state

    def get_obj_by_id(self):
        path = os.path.join(hwk_settings.PATH, self.id)
        with open(path, 'rb') as fr:
            obj = pickle.load(fr)
            return obj


# obj1 = MySql('tank', 'handsome')
# obj1.save()
# obj1.get_obj_by_id()
# print(obj1.__dict__)

obj2 = MySql.ince()
obj2.save()
obj2.get_obj_by_id()
print(obj2.__dict__)

# 2、定义一个类：圆形，该类有半径，周长，面积等属性，将半径隐藏起来，将周长与面积开放
import cmath


class Circle:
    def __init__(self, radius):
        self.__radius = radius

    @property
    def area(self):
        return cmath.pi * self.__radius ** 2

    @property
    def perimeter(self):
        return 2 * cmath.pi * self.__radius


c = Circle(5)
print(c.area)
print(c.perimeter)

# 3、使用abc模块定义一个phone抽象类 并编写一个具体的实现类
import abc


class Phone(metaclass=abc.ABCMeta):
    @abc.abstractmethod
    def call(self):
        pass


class Iphone(Phone):
    def call(self):
        print('使用ios系统及A11处理器打电话')


i = Iphone()
i.call()

'''
4、着手编写选课系统作业:http://www.cnblogs.com/linhaifeng/articles/6182264.html#_label15
'''