def encode(arg): ''' Given that we're converting between variable formats, manual typechecking seems excusable here ''' return { int : lambda x: 'i%ie' % x, str : lambda x: '%i:%s' % (len(x), x), list : lambda x: 'l%se' % ''.join(map(encode, arg)), dict : lambda x: 'd%se' % ''.join(''.join(map(encode, i)) for i in arg.items()) }[type(arg)](arg)def _eat_str(s): length,s = s.split(':', 1) length = int(length) return (s[:length], s[length:])def _eat_int(s): val, s = s.split('e', 1) return int(val), sdef _eat_list(s): r = [] while s[0] is not 'e': val, s = _eat_all(s) r.append(val) return r, s[1:]def _eat_dict(s): r = {} while s[0] is not 'e': k,s = _eat_all(s) v,s = _eat_all(s) r[k] = v return r, s[1:]def _eat_all(s): if s[0] in 'lid': val, s = {'l': _eat_list, 'i': _eat_int, 'd': _eat_dict}[s[0]](s[1:]) else: val, s = _eat_str(s) if len(s): return (val, s) return valdef decode(s): try: val = _eat_all(s) if type(val) is tuple: #should NOT be a tuple, _eat_all would only return a list, dict, #or scalar raise ValueError, val[1] return val except ValueError, e: raise ValueError, 'Error somewhere in "%s"' % e