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import sys
import argparse
class ArgumentUsageError(Exception):
"""Exception class you can raise (and catch) in order to show the help"""
def __init__(self, message, subcommand=None):
self.message = message
self.subcommand = subcommand
class ArgumentParser(argparse.ArgumentParser):
"""Our own version of argparse's ArgumentParser"""
def error(self, message):
sys.stderr.write('ERROR: %s\n' % message)
self.print_help()
sys.exit(2)
def error_subcommand(self, message, subcommand):
if subcommand:
for action in self._actions:
if isinstance(action, argparse._SubParsersAction):
for choice, subparser in action.choices.items():
if choice == subcommand:
subparser.error(message)
return
self.error(message)
def add_subparsers(self, *args, **kwargs):
ret = super(ArgumentParser, self).add_subparsers(*args, **kwargs)
ret._parser_class = ArgumentSubParser
return ret
class ArgumentSubParser(ArgumentParser):
def parse_known_args(self, args=None, namespace=None):
# This works around argparse not handling optional positional arguments being
# intermixed with other options. A pretty horrible hack, but we're not left
# with much choice given that the bug in argparse exists and it's difficult
# to subclass.
# Borrowed from http://stackoverflow.com/questions/20165843/argparse-how-to-handle-variable-number-of-arguments-nargs
# with an extra workaround (in format_help() below) for the positional
# arguments disappearing from the --help output, as well as structural tweaks.
# Originally simplified from http://bugs.python.org/file30204/test_intermixed.py
positionals = self._get_positional_actions()
for action in positionals:
# deactivate positionals
action.save_nargs = action.nargs
action.nargs = 0
namespace, remaining_args = super(ArgumentSubParser, self).parse_known_args(args, namespace)
for action in positionals:
# remove the empty positional values from namespace
if hasattr(namespace, action.dest):
delattr(namespace, action.dest)
for action in positionals:
action.nargs = action.save_nargs
# parse positionals
namespace, extras = super(ArgumentSubParser, self).parse_known_args(remaining_args, namespace)
return namespace, extras
def format_help(self):
# Quick, restore the positionals!
positionals = self._get_positional_actions()
for action in positionals:
if hasattr(action, 'save_nargs'):
action.nargs = action.save_nargs
return super(ArgumentParser, self).format_help()
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