@class_common_init(re_topic_url)<EOL><INDENT>def __init__(self, url, name=None, session=None):<DEDENT>
self.url = url<EOL>self._session = session<EOL>self._name = name<EOL>self._id = int(re_topic_url.match(self.url).group(<NUM_LIT:1>))<EOL>
创建话题类实例.

        :param url: 话题url
        :param name: 话题名称，可选
        :return: Topic