New submission from Wojciech Muła <wojciech_m...@poczta.onet.pl>:
Hi, sometimes it is needed to grab variable, but limited, number of options.
For example --point could accept 2, 3 or 4 values: (x,y) or (x,y,z) or
(x,y,z,w). Current version of argparse requires postprocessing:
parser.add_argument('--point', action='append', default=[])
nmps = parser.parse_args()
if not (2 <= len(nmsp.point) <= 4):
raise argparse.ArgumentTypeError("--point expects 2, 3 or 4
values")
I propose to allow pass range of options count to nargs, including
lower/upper bound. For example:
parser.add_argument('--point', nargs=(2,4) ) # from 2 to 4
parser.add_argument('--foo', nargs=(9, None) ) # at least 9
parser.add_argument('--bar', nargs=(None, 7) ) # at most 7
nmsp = parser.parse_args()
I've attached tests and patch made against Python3.2 lib from Debian.
w.
----------
components: Library (Lib)
files: argparse-nargs.patch
keywords: patch
messages: 129714
nosy: wm
priority: normal
severity: normal
status: open
title: argparse: nargs could accept range of options count
type: feature request
versions: Python 3.2, Python 3.3
Added file: http://bugs.python.org/file20947/argparse-nargs.patch
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<http://bugs.python.org/issue11354>
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