argparse subparser单片帮助输出

Question

我的argparse在顶层只有3个标志(store_true),其他一切都是通过subparsers处理的.当我运行时myprog.py --help,输出显示所有子命令的列表,如normal , {sub1, sub2, sub3, sub4, ...}. 所以,默认工作很好......

我通常记不起我需要的确切子命令名称及其所有选项.所以我最终做了两次帮助查找:

myprog.py --help
myprog.py sub1 --help

我经常这样做,我决定把它塞进一步.我宁愿让我的顶级帮助输出一个巨大的摘要,然后我手动滚动列表.我觉得它要快得多(至少对我来说).

我正在使用RawDescriptionHelpFormatter,并手动输入长帮助输出.但是现在我有很多子命令,它变得很难管理.

有没有办法只用一个程序调用获得详细的帮助输出？

如果没有,我如何迭代我的argparse实例的子分析器,然后从每个实例中单独检索帮助输出(之后我将粘合在一起)？

---

这是我的argparse设置的快速概述.我清理/剥离了相当多的代码,所以如果没有一些帮助,这可能无法运行.

parser = argparse.ArgumentParser(
        prog='myprog.py',
        formatter_class=argparse.RawDescriptionHelpFormatter,
        description=textwrap.dedent(""" You can manually type Help here """) )

parser.add_argument('--debuglog', action='store_true', help='Verbose logging for debug purposes.')
parser.add_argument('--ipyonexit', action='store_true', help='Drop into an embeded Ipython session instead of exiting command.')

subparser = parser.add_subparsers()

### --- Subparser B
parser_b = subparser.add_parser('pdfreport', description="Used to output reports in PDF format.")
parser_b.add_argument('type', type=str, choices=['flatlist', 'nested', 'custom'],
                        help="The type of PDF report to generate.")
parser_b.add_argument('--of', type=str, default='',
                        help="Override the path/name of the output file.")
parser_b.add_argument('--pagesize', type=str, choices=['letter', '3x5', '5x7'], default='letter',
                        help="Override page size in output PDF.")
parser_b.set_defaults(func=cmd_pdf_report)

### ---- Subparser C
parser_c = subparser.add_parser('dbtables', description="Used to perform direct DB import/export using XLS files.")
parser_c.add_argument('action', type=str, choices=['push', 'pull', 'append', 'update'],
                        help="The action to perform on the Database Tables.")
parser_c.add_argument('tablename', nargs="+",
                        help="The name(s) of the DB-Table to operate on.")
parser_c.set_defaults(func=cmd_db_tables)

args = parser.parse_args()
args.func(args)

Answer 1

这有点棘手,因为argparse没有直接暴露定义的子解析器列表.但这是可以完成的:

import argparse

# create the top-level parser
parser = argparse.ArgumentParser(prog='PROG')
parser.add_argument('--foo', action='store_true', help='foo help')
subparsers = parser.add_subparsers(help='sub-command help')

# create the parser for the "a" command
parser_a = subparsers.add_parser('a', help='a help')
parser_a.add_argument('bar', type=int, help='bar help')

# create the parser for the "b" command
parser_b = subparsers.add_parser('b', help='b help')
parser_b.add_argument('--baz', choices='XYZ', help='baz help')
# print main help
print(parser.format_help())

# retrieve subparsers from parser
subparsers_actions = [
    action for action in parser._actions 
    if isinstance(action, argparse._SubParsersAction)]
# there will probably only be one subparser_action,
# but better save than sorry
for subparsers_action in subparsers_actions:
    # get all subparsers and print help
    for choice, subparser in subparsers_action.choices.items():
        print("Subparser '{}'".format(choice))
        print(subparser.format_help())

这个例子适用于python 2.7和python 3.示例解析器来自argparse子命令的Python 2.7文档.

剩下要做的唯一事情就是为完整的帮助添加一个新参数,或者替换内置的-h/--help.

Answer 2

这是完整的自定义帮助处理程序(几乎所有代码来自@Adaephon答案):

import argparse


class _HelpAction(argparse._HelpAction):

    def __call__(self, parser, namespace, values, option_string=None):
        parser.print_help()

        # retrieve subparsers from parser
        subparsers_actions = [
            action for action in parser._actions
            if isinstance(action, argparse._SubParsersAction)]
        # there will probably only be one subparser_action,
        # but better save than sorry
        for subparsers_action in subparsers_actions:
            # get all subparsers and print help
            for choice, subparser in subparsers_action.choices.items():
                print("Subparser '{}'".format(choice))
                print(subparser.format_help())

        parser.exit()

# create the top-level parser
parser = argparse.ArgumentParser(prog='PROG', add_help=False)  # here we turn off default help action

parser.add_argument('--help', action=_HelpAction, help='help for help if you need some help')  # add custom help

parser.add_argument('--foo', action='store_true', help='foo help')
subparsers = parser.add_subparsers(help='sub-command help')

# create the parser for the "a" command
parser_a = subparsers.add_parser('a', help='a help')
parser_a.add_argument('bar', type=int, help='bar help')

# create the parser for the "b" command
parser_b = subparsers.add_parser('b', help='b help')
parser_b.add_argument('--baz', choices='XYZ', help='baz help')

parsed_args = parser.parse_args()

Answer 3

也许更简单的方法是使用parser.epilog：

def define_parser():
    import argparse
    parser = argparse.ArgumentParser(
        prog='main',
        formatter_class=argparse.RawDescriptionHelpFormatter,
    )
    commands = parser.add_subparsers(
        title="required commands",
        help='Select one of:',
    )    
    command_list = commands.add_parser(
        'list',
        help='List included services',
    )
    command_ensure = commands.add_parser(
        'ensure',
        help='Provision included service',
    )
    command_ensure.add_argument(
        "service",
        help='Service name',
    )
    import textwrap
    parser.epilog = textwrap.dedent(
        f"""\
        commands usage:\n
        {command_list.format_usage()}
        {command_ensure.format_usage()}
        """
    )
    return parser

parser = define_parser()

parser.print_help()

这会产生以下输出：

usage: main [-h] {list,ensure} ...

optional arguments:
  -h, --help     show this help message and exit

required commands:
  {list,ensure}  Select one of:
    list         List included services
    ensure       Provision included service

commands usage:

usage: main list [-h]

usage: main ensure [-h] service