Getting "AttributeError: 'tuple' object has no attribute" and fail to see why

Question

I'm stuck using python 2.4 for this project so I'm using optparse. Getting the following error when running this code:

Traceback (most recent call last):
  File "./clientNFSLatMonME.py", line 49, in ?
    debug,verbose,interval = parseOptions()
  File "./clientNFSLatMonME.py", line 43, in parseOptions
    if (args.interval < 1) or (args.interval > MAX_INTERVAL):
AttributeError: 'tuple' object has no attribute 'interval'

Code is as follows:

MAX_INTERVAL = 1800

def parseOptions():

    parser = OptionParser()
    parser.add_option("-d", "--debug",    dest="debug",    action="store_true", help="enable additional debugging output")
    parser.add_option("-v", "--verbose",  dest="verbose",  action="store_true", help="enable additional console output")
    parser.add_option("-i", "--interval", dest="interval", action="store", type="int", default=900, help="specify the time interval, default is 900, maximum is 1800")

    args = parser.parse_args()

    if (args.interval < 1) or (args.interval > MAX_INTERVAL):
        print "Error: interval must be between 1 and " + str(MAX_INTERVAL) + ", terminating."
        system.exit(1)

    return args.debug, args.verbose, args.interval

debug,verbose,interval = parseOptions()

Answer 1

The parser.parse_args() method returns a tuple, containing parsed options and the remaining arguments.

Unpack that tuple; the convention is to use options for the parsed switches and args for

options, args = parser.parse_args()

and use options to refer to parsed command line switches:

if options.interval < 1 or options.interval > MAX_INTERVAL:
    # ...

return options.debug, options.verbose, options.interval

That range check can be expressed using a chained comparison too:

if not (0 > options.interval >= MAX_INTERVAL):
    # ...