En Thu, 28 Apr 2011 04:24:46 -0300, Andrew Berg
<bahamutzero8...@gmail.com> escribió:
I've set up groups of arguments for a script I'm writing, and any time I
give an argument a value, it gets stored as a list instead of a string,
even if I explicitly tell it to store a string. Arguments declared with
other types (e.g. float, int) and default values are stored as expected.
For example:
vidin_args=parser.add_argument_group('Video Input Options', 'Various
options that control how the video file is demuxed/decoded.')
vidin_args.add_argument('-m', dest='vmode', nargs=1, type=str,
metavar='video_mode', choices=['ntsc', 'pal', 'film', 'ivtc'],
default='ntsc', help='Valid values are "ntsc", "pal", "film" and
"ivtc".')
...more arguments...
opts=parser.parse_args()
If I assign a value on the command line (e.g. -m pal), opts.vmode is a
list, otherwise it's a string. This is pretty bad since I can't know
whether to get opts.vmode or opts.vmode[0] later in the script. I could
loop through all the options and convert each option to a string, but
that's not really something I want to do, especially if I start adding
more options.
That's because of nargs=1. From the argparse documentation: [1]
Note that nargs=1 produces a list of one item. This is different from the
default, in which the item is produced by itself.
So, just remove nargs=1 from add_argument()
[1] http://docs.python.org/py3k/library/argparse.html#nargs
--
Gabriel Genellina
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