Argparse: nested optional argument, force --arg=val over --arg val, single occurrence, optional argument order

问题

The program should be executed as follows:

./interpret.py --help | --source=FILE1 [--stats=FILE2 [--vars] [--insts]]

the rules are:

--help has to be the only argument if passed
--source=FILE1 has to be provided and can't be passed like --source FILE1
if --vars or --insts is provided, then --stats=FILE2 has to be provided
the order of --vars and --insts matters, therefore has to be stored
multiple occurrence of an argument is forbidden

I have read multiple tutorials and SO answers, but they don't even remotly cover my problem. Managed to do the following:

# parses command line arguments
def parse_args():
    parser = argparse.ArgumentParser(add_help=False)
    parser.add_argument('--source')
    parser.add_argument('--stats')
    parser.add_argument('--vars', action='count', default=0)
    parser.add_argument('--insts', action='count', default=0)
    parser.add_argument('--help', action='count', default=0)

    try:
        args = parser.parse_args()
    catch SystemExit:
        exit(ERR_PARAM)

    if args.help > 0:
        if args.source != None or args.stats != None or (args.help + args.vars + args.insts) != 1:
            exit(ERR_PARAM)

        manual()
        exit(0)

    if args.source == None:
        exit(ERR_PARAM)

    if args.vars > 1 or args.insts > 1:
        exit(ERR_PARAM)

    if (args.vars + args.insts) > 0 and args.stats == None:
        exit(ERR_PARAM)

    return args

The code has the following problems:

--source and --stats can be passed multiple times
--source and --stats can be passed like --source FILE1
the order of --vars --insts is not stored anywhere

来源：https://stackoverflow.com/questions/49506868/argparse-nested-optional-argument-force-arg-val-over-arg-val-single-occur

标签

python

command-line-arguments

argparse