Hiding selected subcommands using argparse

问题

I am using argparse and have set-up subcommands to my program. I have created sub-parsers to define these sub-commands. I have some admin commands that shouldn't be shown to users in the help screen. I know we could hide arguments of a sub-command, but I don't know how we could hide few of the subcommands from showing up in the help list.

Here's my code snippet,

parser = argparse.ArgumentParser(prog='myProg',
                                    description=desc,
                                   formatter_class=argparse.RawDescriptionHelpFormatter)

subparsers = parser.add_subparsers(dest='sub_parser_name')


myProg_query.add_subparser(subparsers)
myProg_update.add_subparser(subparsers)
myProg_configure.add_subparser(subparsers)
myProg_result.add_subparser(subparsers)

When I run the help command, I get this

%> myProg --help
usage: myProg [-h] 

positional arguments:
{query,update,configure,result}
query               query information
update              Update 
configure           Configure system
result              tabulate the result

From the help output, I would want to display only "query" and "result" to the user. I tried to use argparse.SUPPRESS in add_subparser method, but it would hide all the subcommands. Whatever I searched only talked about hiding individual arguments of each sub-command, but not about hiding sub-command. I might have to create a custom formatter method, but wanted to check if there were any other way to achieve this.

回答1:

metavar might do the trick:

import argparse
parser = argparse.ArgumentParser()
sp = parser.add_subparsers(metavar='{cmd1,cmd2}')
sp1 = sp.add_parser('cmd1')
sp2 = sp.add_parser('cmd2')
sp3 = sp.add_parser('cmd3')
parser.parse_args()

With this cmd3 does not appear in the usage or help. But it does appear in the error message

error: argument {cmd1,cmd2}: invalid choice: 'cmd' (choose from 'cmd1', 'cmd2', 'cmd3')

You may have already discovered this use of help=SUPPRESS. But it requires a custom usage (and possibly description) parameters:

import argparse
parser = argparse.ArgumentParser(usage='%(prog)s [-h] {cmd1,cmd2}')
sp = parser.add_subparsers(help=argparse.SUPPRESS)
sp1 = sp.add_parser('cmd1')
sp2 = sp.add_parser('cmd2')
sp3 = sp.add_parser('cmd3')
parser.parse_args()

To the main parser, subparsers look like choices of a positional argument. As best I can tell there isn't a way of selectively suppressing choices.

With this level of question, examining the argparse.py code itself can be more help than the docs. In this case I looked at the code for class _SubParsersAction(Action). That's doubly true if you want to customize the formatter. The existing alternative formatters modify just one or two methods buried deep in the class.

This issue has been raised as a bug issue, http://bugs.python.org/issue22848.

There is a patch that would modify the choices display based on help=SUPPRESS for individual subparsers. But I'm recommending the metavar solution, at least for now. There are other proposed patches for dealing with choices.

回答2:

looks like I found a solution for this issue without any patches for argparse. It's enough to modify 'metavar' and do not set 'help' for the certain subparser.

import argparse

parser = argparse.ArgumentParser()
subparsers = parser.add_subparsers(title='commands', metavar='{command}')

command = subparsers.add_parser("command",
                                help='command help.',
                                description='command description.')
suppress_command = subparsers.add_parser("suppress_command",
                                         help=argparse.SUPPRESS,
                                         description='suppress command.')
hidden_command = subparsers.add_parser("hidden_command",
                                       description='Hidden command.')

This results in

[root@localhost ~]# parser -h
usage: parser [-h] {command} ...

optional arguments:
-h, --help        print help message and exit

commands:
{command}
    command           command help.
    suppress_command  ==SUPPRESS==

[root@localhost ~]# parser hidden_command -h
usage: parser hidden_command [-h]

Hidden command.

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

来源：https://stackoverflow.com/questions/21692395/hiding-selected-subcommands-using-argparse

标签

python

argparse