bpo-26510: make argparse subparsers required by default (#3027) · pythoncapi/cpython@aaf6fc0 · GitHub
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bpo-26510: make argparse subparsers required by default (python#3027)
This fixes a regression from Python 2. To get optional subparsers, use the new parameter ``add_subparsers(required=False)``. Patch by Anthony Sottile.
1 parent 19e4d93 commit aaf6fc0

4 files changed

Lines changed: 46 additions & 3 deletions

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‎Doc/library/argparse.rst‎

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‎Lib/argparse.py‎

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@@ -1066,6 +1066,7 @@ def __init__(self,
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prog,
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parser_class,
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dest=SUPPRESS,
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required=True,
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help=None,
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metavar=None):
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@@ -1079,6 +1080,7 @@ def __init__(self,
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dest=dest,
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nargs=PARSER,
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choices=self._name_parser_map,
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required=required,
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help=help,
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metavar=metavar)
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‎Lib/test/test_argparse.py‎

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@@ -1807,7 +1807,7 @@ def _get_parser(self, subparser_help=False, prefix_chars=None,
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'bar', type=float, help='bar help')
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# check that only one subparsers argument can be added
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subparsers_kwargs = {}
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subparsers_kwargs = {'required': False}
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if aliases:
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subparsers_kwargs['metavar'] = 'COMMAND'
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subparsers_kwargs['title'] = 'commands'
@@ -1907,6 +1907,41 @@ def test_dest(self):
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self.assertEqual(NS(foo=False, bar='1', baz='2'),
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parser.parse_args('1 2'.split()))
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def _test_required_subparsers(self, parser):
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# Should parse the sub command
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ret = parser.parse_args(['run'])
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self.assertEqual(ret.command, 'run')
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# Error when the command is missing
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self.assertArgumentParserError(parser.parse_args, ())
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def test_required_subparsers_via_attribute(self):
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parser = ErrorRaisingArgumentParser()
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subparsers = parser.add_subparsers(dest='command')
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subparsers.required = True
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subparsers.add_parser('run')
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self._test_required_subparsers(parser)
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def test_required_subparsers_via_kwarg(self):
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parser = ErrorRaisingArgumentParser()
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subparsers = parser.add_subparsers(dest='command', required=True)
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subparsers.add_parser('run')
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self._test_required_subparsers(parser)
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def test_required_subparsers_default(self):
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parser = ErrorRaisingArgumentParser()
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subparsers = parser.add_subparsers(dest='command')
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subparsers.add_parser('run')
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self._test_required_subparsers(parser)
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def test_optional_subparsers(self):
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parser = ErrorRaisingArgumentParser()
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subparsers = parser.add_subparsers(dest='command', required=False)
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subparsers.add_parser('run')
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# No error here
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ret = parser.parse_args(())
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self.assertIsNone(ret.command)
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def test_help(self):
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self.assertEqual(self.parser.format_usage(),
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'usage: PROG [-h] [--foo] bar {1,2,3} ...\n')

‎Misc/NEWS.d/next/Library/2017-09-19-13-29-29.bpo-26510.oncW6V.rst‎

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