Python argparse:很多选择导致丑陋的帮助输出

Question

我有这个代码,我通常很高兴:

import argparse

servers = [ "ApaServer", "BananServer", "GulServer", "SolServer", "RymdServer",
            "SkeppServer", "HavsServer", "PiratServer", "SvartServer", "NattServer", "SovServer" ]

parser = argparse.ArgumentParser(description="A program to update components on servers.")
group = parser.add_mutually_exclusive_group()
group.add_argument('-l', '--list', dest="update", action='store_false', default=False, help='list server components')
group.add_argument('-u', '--updatepom', dest="update", action='store_true', help='update server components')
parser.add_argument('-o', '--only', nargs='*', choices=servers, help='Space separated list of case sensitive server names to process')
parser.add_argument('-s', '--skip', nargs='*', choices=servers, help='Space separated list of case sensitive server names to exclude from processing')
args = parser.parse_args()

我喜欢选择=服务器为我验证输入中的服务器名称,所以我不必这样做.但是,有这么多有效的选择会使帮助输出看起来很糟糕:

usage: args.py [-h] [-l | -u]
               [-o [{ApaServer,BananServer,GulServer,SolServer,RymdServer,SkeppServer,HavsServer,PiratServer,SvartServer,NattServer,SovServer} [{ApaServer,BananServer,GulServer,SolServer,RymdServer,SkeppServer,HavsServer,PiratServer,SvartServer,NattServer,SovServer} ...]]]
               [-s [{ApaServer,BananServer,GulServer,SolServer,RymdServer,SkeppServer,HavsServer,PiratServer,SvartServer,NattServer,SovServer} [{ApaServer,BananServer,GulServer,SolServer,RymdServer,SkeppServer,HavsServer,PiratServer,SvartServer,NattServer,SovServer} ...]]]

A program to update components on servers.

optional arguments:
  -h, --help            show this help message and exit
  -l, --list            list server components
  -u, --updatepom       update server components
  -o [{ApaServer,BananServer,GulServer,SolServer,RymdServer,SkeppServer,HavsServer,PiratServer,SvartServer,NattServer,SovServer} [{ApaServer,BananServer,GulServer,SolServer,RymdServer,SkeppServer,HavsServer,PiratServer,SvartServer,NattServer,SovServer} ...]], --only [{ApaServer,BananServer,GulServer,SolServer,RymdServer,SkeppServer,HavsServer,PiratServer,SvartServer,NattServer,SovServer} [{ApaServer,BananServer,GulServer,SolServer,RymdServer,SkeppServer,HavsServer,PiratServer,SvartServer,NattServer,SovServer} ...]]
                        Space separated list of case sensitive server names to
                        process
  -s [{ApaServer,BananServer,GulServer,SolServer,RymdServer,SkeppServer,HavsServer,PiratServer,SvartServer,NattServer,SovServer} [{ApaServer,BananServer,GulServer,SolServer,RymdServer,SkeppServer,HavsServer,PiratServer,SvartServer,NattServer,SovServer} ...]], --skip [{ApaServer,BananServer,GulServer,SolServer,RymdServer,SkeppServer,HavsServer,PiratServer,SvartServer,NattServer,SovServer} [{ApaServer,BananServer,GulServer,SolServer,RymdServer,SkeppServer,HavsServer,PiratServer,SvartServer,NattServer,SovServer} ...]]
                        Space separated list of case sensitive server names to
                        exclude from processing

如果我需要,你会推荐哪种方式:

• 很好(主要)自动生成的帮助输出
• 验证给予-o或-s选项的条目是否在servers.

奖金:

• 是否可以对服务器名称进行不区分大小写的字符串匹配？

附加

我尝试使用michaelfilms建议,-o -s从上面的输出中删除选项,并添加此部分:

server optional arguments:
  Valid server names are: ApaServer, BananServer, GulServer, SolServer,
  RymdServer, SkeppServer, HavsServer, PiratServer, SvartServer,
  NattServer, SovServer

我认为它看起来很不错,但我真的需要提供帮助-o和-s选项,否则用户不会知道它们.所以我还没有使用这种方法.

Answer 1

我基本上重复了Ernest所说的 - 为了避免丑陋的长选择列表,为基于选择的参数设置metavar =''(尽管它不会消除参数和逗号之间的空白(例如-o ,代替-o,).然后,您可以在一般描述中详细描述可用选项(如果您希望它们列出明显的缩进,则RawDescriptionHelpFormatter在此处很有用).

我不明白为什么欧内斯特的答案被否决了.这段代码

import argparse

servers = [ "ApaServer", "BananServer", "GulServer", "SolServer", "RymdServer",
            "SkeppServer", "HavsServer", "PiratServer", "SvartServer", "NattServer", "SovServer" ]

parser = argparse.ArgumentParser(description="A program to update components on servers.")
group = parser.add_mutually_exclusive_group()
group.add_argument('-l', '--list', dest="update", action='store_false', default=False, help='list server components')
group.add_argument('-u', '--updatepom', dest="update", action='store_true', help='update server components')
parser.add_argument('-o', '--only', choices=servers, help='Space separated list of case sensitive server names to process.  Allowed values are '+', '.join(servers), metavar='')
parser.add_argument('-s', '--skip', choices=servers, help='Space separated list of case sensitive server names to exclude from processing.  Allowed values are '+', '.join(servers), metavar='')
args = parser.parse_args()

产生以下帮助输出

usage: run.py [-h] [-l | -u] [-o] [-s]

A program to update components on servers.

optional arguments:
  -h, --help       show this help message and exit
  -l, --list       list server components
  -u, --updatepom  update server components
  -o , --only      Space separated list of case sensitive server names to
                   process. Allowed values are ApaServer, BananServer,
                   GulServer, SolServer, RymdServer, SkeppServer, HavsServer,
                   PiratServer, SvartServer, NattServer, SovServer
  -s , --skip      Space separated list of case sensitive server names to
                   exclude from processing. Allowed values are ApaServer,
                   BananServer, GulServer, SolServer, RymdServer, SkeppServer,
                   HavsServer, PiratServer, SvartServer, NattServer, SovServer

希望原始帖子正在寻找.

Answer 2

没有必要继承任何东西.只需传递一个metavar参数,其中包含您要在帮助消息中显示的字符串.

有关详细信息,请参阅argparse文档.

Answer 3

我有同样的问题,作为解决方法,我使用epilog来描述每个选项.我不得不使用argparse.RawTextHelpFormatter,它允许您指定epilog是预格式化的.

def choicesDescriptions():
   return """
Choices supports the following: 
   choice1         - the FIRST option
   choice2         - the SECOND option
   ...
   choiceN         - the Nth option
"""

def getChoices():
   return ["choice1", "choice2", ..., "choiceN"]

parser = argparse.ArgumentParser(formatter_class=argparse.RawTextHelpFormatter, epilog=choicesDescriptions())
parser.add_argument(
   'choices', 
   choices=getChoices(),
   help='Arg choice.  See the choices options below'
   )

args = parser.parse_args()
print(args)

Answer 4

在原始问题中选项列表非常长的情况下这无济于事,但对于像我这样的人来说,遇到这个问题寻找一种方法来将中等长度的选项字符串分成两行,这是我的解:

import argparse

class CustomFormatter(argparse.HelpFormatter):
    """Custom formatter for setting argparse formatter_class. Identical to the
    default formatter, except that very long option strings are split into two
    lines.
    """

    def _format_action_invocation(self, action):
        if not action.option_strings:
            metavar, = self._metavar_formatter(action, action.dest)(1)
            return metavar
        else:
            parts = []
            # if the Optional doesn't take a value, format is:
            #    -s, --long
            if action.nargs == 0:
                parts.extend(action.option_strings)
            # if the Optional takes a value, format is:
            #    -s ARGS, --long ARGS
            else:
                default = action.dest.upper()
                args_string = self._format_args(action, default)
                for option_string in action.option_strings:
                    parts.append('%s %s' % (option_string, args_string))
            if sum(len(s) for s in parts) < self._width - (len(parts) - 1) * 2:
                return ', '.join(parts)
            else:
                return ',\n  '.join(parts)

此代码将覆盖缺省的argparse.HelpFormatter方法_format_action_invocation,并且与最后四行中的默认实现相同.

默认格式化程序行为:

parser = argparse.ArgumentParser(description="Argparse default formatter.")
parser.add_argument('-a', '--argument', help='not too long')
parser.add_argument('-u', '--ugly', choices=range(20), help='looks messy')
parser.print_help()

输出:

usage: test.py [-h] [-a ARGUMENT]
               [-u {0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19}]

Argparse default formatter.

optional arguments:
  -h, --help            show this help message and exit
  -a ARGUMENT, --argument ARGUMENT
                        not too long
  -u {0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19}, --ugly {0,1,2,3,4,5,6,
7,8,9,10,11,12,13,14,15,16,17,18,19}
                        looks messy

自定义格式化程序行为

parser = argparse.ArgumentParser(description="Argparse custom formatter.",
                                 formatter_class=CustomFormatter)
parser.add_argument('-a', '--argument', help='not too long')
parser.add_argument('-l', '--less-ugly', choices=range(20), help='less messy')

输出:

usage: test.py [-h] [-a ARGUMENT]
               [-l {0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19}]

Argparse custom formatter.

optional arguments:
  -h, --help            show this help message and exit
  -a ARGUMENT, --argument ARGUMENT
                        not too long
  -l {0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19},
  --less-ugly {0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19}
                        less messy

Answer 5

为什么不使用 parser.add_argument_group 为基于服务器的选项创建一个组，并给出一个描述 arg 显示可能的选择列表？然后将 argparse.SUPPRESS 传递到每个单独选项的帮助中。我相信这会给你你想要的。