python面向对象（类的使用）

import datetime
class Book:
    def __init__(self,title,price = 0.0,publisher = '',pubdate = datetime.date.today()):#初始化器,构造函数初始化内成员用的
        self.title = title,
        self.price = price
        self.publisher = publisher
        self.pubdate = pubdate


    def __repr__(self):
        print('图书{}at{}'.format(self.title,id(self)))

    def print_informance(self):
        print('书名：{}'.format(self.title))
        print('价格：{}'.format(self.price))
        print('出版社：{}'.format(self.publisher))
        print('出版日期：{}'.format(self.pubdate))



book1 = Book('Python入门',88,'清华大学出版社',datetime.date(2020,2,2)) #实例化
book2 = Book('QDN')

Book.print_informance(book1)