[py]python面向對象__str__一探究竟

init實例化對象時執行

str打印對象名時候執行

探究字典

• 查dir({})內置屬性方法
  
• 字典的返回值
  
  兩種方法,返回的值得類型不一樣.
• 對比類
  

重點來了…

默認是init內容,以str的格式返回

技巧

參考:

http://blog.csdn.net/xiaofeng_yan/article/details/6616743
https://www.liaoxuefeng.com/wiki/001374738125095c955c1e6d8bb493182103fac9270762a000/0013946328809098c1be08a2c7e4319bd60269f62be04fa000

附一段flask 對sqlite操作的封裝模型

class User(object):
    def __init__(self, id, name):
        self.id = id
        self.name = name

    def save(self):
        sql = 'insert into user VALUES (?,?)'
        conn = get_conn()
        cur = conn.cursor()
        cur.execute(sql, (self.id, self.name))
        conn.commit()
        cur.close()
        conn.close()

    @staticmethod
    def query():
        sql = 'select * from user'
        conn = get_conn()
        cur = conn.cursor()
        rows = cur.execute(sql)
        users = []
        for row in rows:
            user = User(row[0], row[1])
            users.append(user)
        conn.commit()
        cur.close()
        conn.close()
        return users

    def __str__(self):
        return 'id:{}--name:{}'.format(self.id, self.name)