GeezerVison is showing github.com — bpo-26510: Allow argparse add_subparsers to take `required` kwarg. by asottile · Pull Request #3027 · python/cpython
bpo-26510: Allow argparse add_subparsers to take required kwarg.
#3027
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@@ -1539,8 +1539,8 @@ Sub-commands
.. method:: ArgumentParser.add_subparsers([title], [description], [prog], \
[parser_class], [action], \
[option_string], [dest], [help], \
[metavar])
[option_string], [dest], [required] \
[help], [ metavar])
Many programs split up their functionality into a number of sub-commands,
for example, the ``svn`` program can invoke sub-commands like ``svn
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@@ -1576,6 +1576,9 @@ Sub-commands
* dest_ - name of the attribute under which sub-command name will be
stored; by default ``None`` and no value is stored
* required_ - Whether or not a subcommand must be provided, by default
``True``.
* help_ - help for sub-parser group in help output, by default ``None``
* metavar_ - string presenting available sub-commands in help; by default it
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@@ -1066,6 +1066,7 @@ def __init__(self,
prog,
parser_class,
dest=SUPPRESS,
required=True,
help=None,
metavar=None):
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For maximum backward compatibility, the new parameter should be added to the end.
(I don’t personnally write calls like something('abc', SUPPRESS, True, None, None) but they are supported, and should not be broken when possible.)
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add_subparsers itself takes no keyword arguments so I don't think there's a concern of the private api here.
> >> parser .add_subparsers ('foo' , True , False )
Traceback (most recent call last ):
File "<stdin>" , line 1 , in < module >
TypeError : add_subparsers () takes 1 positional argument but 4 were given (the 1 positional argument here being self)
The ordering I chose was intentional to match the signatures in the rest of the file.
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@merwok do I monty-python it up now? I'm unclear on the process for dismissing a review :P
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The review holding this up is «please update docs and news» :)
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whoops totally missed that! I'll get right on it :)
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@@ -1079,6 +1080,7 @@ def __init__(self,
dest=dest,
nargs=PARSER,
choices=self._name_parser_map,
required=required,
help=help,
metavar=metavar)
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@@ -1807,7 +1807,7 @@ def _get_parser(self, subparser_help=False, prefix_chars=None,
'bar', type=float, help='bar help')
# check that only one subparsers argument can be added
subparsers_kwargs = {}
subparsers_kwargs = {'required': False }
if aliases:
subparsers_kwargs['metavar'] = 'COMMAND'
subparsers_kwargs['title'] = 'commands'
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@@ -1907,6 +1907,41 @@ def test_dest(self):
self.assertEqual(NS(foo=False, bar='1', baz='2'),
parser.parse_args('1 2'.split()))
def _test_required_subparsers(self, parser):
# Should parse the sub command
ret = parser.parse_args(['run'])
self.assertEqual(ret.command, 'run')
# Error when the command is missing
self.assertArgumentParserError(parser.parse_args, ())
def test_required_subparsers_via_attribute(self):
parser = ErrorRaisingArgumentParser()
subparsers = parser.add_subparsers(dest='command')
subparsers.required = True
subparsers.add_parser('run')
self._test_required_subparsers(parser)
def test_required_subparsers_via_kwarg(self):
parser = ErrorRaisingArgumentParser()
subparsers = parser.add_subparsers(dest='command', required=True)
subparsers.add_parser('run')
self._test_required_subparsers(parser)
def test_required_subparsers_default(self):
parser = ErrorRaisingArgumentParser()
subparsers = parser.add_subparsers(dest='command')
subparsers.add_parser('run')
self._test_required_subparsers(parser)
def test_optional_subparsers(self):
parser = ErrorRaisingArgumentParser()
subparsers = parser.add_subparsers(dest='command', required=False)
subparsers.add_parser('run')
# No error here
ret = parser.parse_args(())
self.assertIsNone(ret.command)
def test_help(self):
self.assertEqual(self.parser.format_usage(),
'usage: PROG [-h] [--foo] bar {1,2,3} ...\n')
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@@ -0,0 +1,3 @@
argparse subparsers are now required by default. This matches behaviour in Python 2.
For optional subparsers, use the new parameter ``add_subparsers(required=False)``.
Patch by Anthony Sottile.
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