个人认为WeatherSaxHandler中应该是尽可能多地采集信息，parse_weather中是筛选目前可用信息，并通过一定格式返回到更上层，这样我们就能以最小的改动跟随上层的需求变动。

class WeatherSaxHandler(object):
    info = {}
    cnt = {}
    def _attrs_filter(self, attrs):
        for x in attrs:
            t = attrs[x]
            attrs[x] = int(t) if t.isdigit() else t
        return attrs
    def start_element(self, name, attrs):
        if ':' in name:
            attrs = self._attrs_filter(attrs)
            key = name[name.index(':')+1::]
            if key not in self.info:
                self.info[key] = attrs
            else:
                if key not in self.cnt:
                    self.cnt[key] = 1
                else:
                    self.cnt[key] += 1
                self.info[key+'(%d)'% self.cnt[key]] = attrs
    def end_element(self, name):
        pass
    def char_data(self, text):
        pass
def parse_weather(xml):
    weatherHandler = WeatherSaxHandler()
    weatherParser = ParserCreate()
    weatherParser.StartElementHandler = weatherHandler.start_element
    weatherParser.EndElementHandler = weatherHandler.end_element
    weatherParser.CharacterDataHandler = weatherHandler.char_data
    weatherParser.Parse(xml)
    info = weatherHandler.info
    return {
        'city':info['location']['city'],
        'country':info['location']['country'],
        'today':info['forecast'],
        'tomorrow':info['forecast(1)']}

info = parse_weather(data)