Python argparse required=True 但 --version 功能? [英] Python argparse required=True but --version functionality?

问题描述

在我的所有脚本中，我使用标准标志 --help 和 --version，但是我似乎无法弄清楚如何制作 --版本 with parser.add_argument(..., required=True).

In all my scripts I use the standard flags --help and --version, however I cannot seem to figure out how to make a --version with parser.add_argument(..., required=True).

import sys, os, argparse

parser = argparse.ArgumentParser(description='How to get --version to work?')

parser.add_argument('--version', action='store_true', 
                    help='print version information')
parser.add_argument('-H', '--hostname', dest='hostname', required=True, 
                    help='Host name, IP Address')
parser.add_argument('-d', '--database', dest='database', required=True,
                    help='Check database with indicated name')
parser.add_argument('-u', '--username', dest='username', required=True, 
                    help='connect using the indicated username')
parser.add_argument('-p', '--password', dest='password', required=True, 
                    help='use the password to authenticate the connection')

args = parser.parse_args()

if args.version == True:
    print 'Version information here'

$ ./arg.py  --version 
usage: arg.py [-h] [--version] -H HOSTNAME -d DATABASE -u USERNAME -p PASSWORD 
arg.py: error: argument -H/--hostname is required

是的，我希望 --hostname 和其他是必需的，但我总是希望 --version像 --help(和 -h)一样适当地工作.

Yes, I want --hostname and others required, but I always want --version to work appropriately like --help (and -h).

$ ./arg.py  --help   
usage: arg.py [-h] [--version] -H HOSTNAME -d DATABASE -u USERNAME -p PASSWORD

How to get --version to work?

optional arguments:
  -h, --help            show this help message and exit
  --version             print version information
  -H HOSTNAME, --hostname HOSTNAME
                        Host name, IP Address
  -d DATABASE, --database DATABASE
                        Check database with indicated name
  -u USERNAME, --username USERNAME
                        connect using the indicated username
  -p PASSWORD, --password PASSWORD
                        use the password to authenticate the connection

对让 --version 工作有什么帮助吗?

Any help on getting --version to work?

推荐答案

add_argument 有一个特殊的version action 关键字参数(如此处记录:argparse#action).
试试这个(从工作代码复制):

There is a special version action keyword argument to add_argument (As documented here: argparse#action).
Try this (copied from working code):

parser.add_argument('-V', '--version', 
                    action='version',                    
                    version='%(prog)s (version 0.1)')

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