Python MySQL 和上下文管理器：__exit__ 属性错误

Question

使用 Python 2.7.9，我试图排除 mysql 连接和游标的打开和关闭

代码是

class MySQLCursor:
    def __init__(self, commit=False):
        self.commit = commit

    def __enter__(self):
        self.conn = MySQLdb.connect(host=_MYMYSQLHOST,
                                    user=_MYMYSQLUSER,
                                    passwd=_MYMYSQLPASSWD,
                                    db=_MYMYSQLDB)
        self.cursor = self.conn.cursor()
        return self.cursor

    def __exit__(self, exc_type, exc_val, exc_tb):
        if self.commit:
            self.conn.commit()
        self.cursor.close()
        self.conn.close()
        return

使用它作为

with MySQLCursor as cursor:
    cursor.execute("SELECT VERSION()")
    row = cursor.fetchone()
    print "server version:", row[0]

我收到错误消息

AttributeError: __exit__ 

这是 mysql 问题还是上下文管理器问题？

Answer 1

只是做with MySQLCursor() as cursor:- With 语句需要具有__enter__和__exit__方法的类的实例，而不是类本身。