python argparse:nargs +或 *取决于先前的参数
题
我正在编写服务器查询工具,并且我有一些代码可以在最顶部解析参数:
# Parse arguments
p = argparse.ArgumentParser()
g = p.add_mutually_exclusive_group(required=True)
g.add_argument('--odam', dest='query_type', action='store_const',
const='odam', help="Odamex Master query.")
g.add_argument('--odas', dest='query_type', action='store_const',
const='odas', help="Odamex Server query.")
p.add_argument('address', nargs='*')
args = p.parse_args()
# Default master server arguments.
if args.query_type == 'odam' and not args.address:
args.address = [
'master1.odamex.net:15000',
'master2.odamex.net:15000',
]
# If we don't have any addresses by now, we can't go on.
if not args.address:
print "If you are making a server query, you must pass an address."
sys.exit(1)
是否有更好的方法可以做到这一点,最好是在解析器中?最后一个错误看起来有些不合时宜,如果我可以将nargs进行地址做,这将是不错的选择,取决于-odam或 - odas是否传递。我可以创建一个地下店员,但这会使帮助看起来有些奇怪,因为它会抛弃命令的地址部分。
解决方案
您可以使用自定义做到这一点 ArgParse.Action:
import argparse
import sys
class AddressAction(argparse.Action):
def __call__(self, parser, args, values, option = None):
args.address=values
if args.query_type=='odam' and not args.address:
args.address=[
'master1.odamex.net:15000',
'master2.odamex.net:15000',
]
if not args.address:
parser.error("If you are making a server query, you must pass an address.")
p = argparse.ArgumentParser()
g = p.add_mutually_exclusive_group(required=True)
g.add_argument('--odam', dest='query_type', action='store_const',
const='odam', help="Odamex Master query.")
g.add_argument('--odas', dest='query_type', action='store_const',
const='odas', help="Odamex Server query.")
p.add_argument('address', nargs='*', action=AddressAction)
args = p.parse_args()
产量
% test.py --odas
If you are making a server query, you must pass an address.
% test.py --odam
Namespace(address=['master1.odamex.net:15000', 'master2.odamex.net:15000'], query_type='odam')
% test.py --odam 1 2 3
Namespace(address=['1', '2', '3'], query_type='odam')
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