CODEWITHSUNDEEP
pythonargparse
Adam Matan
Adam Matan

Reputation: 136141

Python, argparse: different parameters with different number of arguments

I would like to write a Python script called sync that has three or four modes of operation, each receiving a different number of arguments. For example, 

sync set_version <build> <version_number>
sync get_version <build>
sync has_started <build_1> <build_2> ... <build_n>

I've tried using argparse's subparsers for each mode of operation:

import argparse

parser = argparse.ArgumentParser(description='Build synchronization mechanism')
subparsers = parser.add_subparsers()

parser_get_version = subparsers.add_parser('get_version')
parser_get_version.add_argument('build')

parser_update_version = subparsers.add_parser('update_version')
parser_update_version.add_argument('build')
parser_update_version.add_argument('version')

args = parser.parse_args()
print args

The problem is that the help message is not reflecting the structure of the arguments of each operation modes. Instead, it simply lists the operation modes:

usage: sync.py [-h] {get_version,update_version} ...

Build synchronization mechanism

positional arguments:
  {get_version,update_version}

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

How do I force argparse to display a full help message, with all the subparsers parameters?

Upvotes: 1

Views: 777

Answers (1)

Martijn Pieters
Martijn Pieters

Reputation: 1121416

Each sub-command has it's own help; try sync.py get_version --help, for example.

You'd have to override the help action yourself, and loop over the subcommands and print help for each. This requires some foibling with internal attributes:

class HelpAction(argparse._HelpAction):
     def __call__(self, parser, namespace, values, option_string=None):
         parser.print_help()

         for group in parser._subparsers._group_actions:
             group.choices.values()[0].print_help()

         parser.exit()

parser = argparse.ArgumentParser(description='Build synchronization mechanism',
                                 add_help=False)
parser.add_argument('-h', '--help', action=HelpAction, default=argparse.SUPPRESS,
    help=argparse._('show this help message and exit'))

You probably want to tweak the output some more though.

Upvotes: 1

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