今天写了一个三重 def 的 Python 函数

# decorator wrapper for _Parser()
def Parser(cls, cache = False):
    def _fun(fun):
        def _Fun(*arg, **kw):
            # try get from cache
            if cache and (len(arg) >= 1 or '_id' in kw):
                _id = arg[0] if arg else kw['_id']
                o = Cacher(cls).get(_id)
                if o:
                    return o
            ret = fun(*arg, **kw)
            try:
                ret = _Parser(ret, cls)
            except Exception as e:
                logging.exception('failed to parse')
            return ret
        return _Fun
    return _fun

@Parser(Type, True)
def get_type(_id):
    ...