':param bs4.element.Tag act: è¡šç€ºçšæ·åšæçé¡µé¢åçŽ 
:param Session session: äœ¿çšççœç»äŒè¯
:param Author author: Activity æå±ççšæ·å¯¹è±¡
:return: çšæ·åšæå¯¹è±¡
:rtype: Activity
æ ¹æ®Activity.typeäžåå¯ä»¥è·åäžåå±æ§ïŒå·äœè¯·ç :class:`.ActType`'

def __init__(self, act, session, author):

    self._session = session
    self._author = author
    self._type = ActType.from_str(act.attrs['data-type-detail'])
    useless_tag = act.div.find('a', class_='zg-link')
    if (useless_tag is not None):
        useless_tag.extract()
    attribute = self._get_assemble_method(self.type)(act)
    self._attr = attribute.__class__.__name__.lower()
    setattr(self, self._attr, attribute)
    self._time = datetime.fromtimestamp(int(act['data-time']))
