diff --git a/Doc/library/argparse.rst b/Doc/library/argparse.rst index 51ab8e29ff96d5..ee8562b81770b6 100644 --- a/Doc/library/argparse.rst +++ b/Doc/library/argparse.rst @@ -61,7 +61,8 @@ ArgumentParser objects formatter_class=argparse.HelpFormatter, \ prefix_chars='-', fromfile_prefix_chars=None, \ argument_default=None, conflict_handler='error', \ - add_help=True, allow_abbrev=True, exit_on_error=True) + add_help=True, allow_abbrev=True, exit_on_error=True, \ + suggest_on_error=False) Create a new :class:`ArgumentParser` object. All parameters should be passed as keyword arguments. Each parameter has its own more detailed description @@ -103,6 +104,10 @@ ArgumentParser objects * exit_on_error_ - Determines whether or not ArgumentParser exits with error info when an error occurs. (default: ``True``) + * suggest_on_error_ - Enables suggestions for mistyped argument choices + and subparser names (default: ``False``) + + .. versionchanged:: 3.5 *allow_abbrev* parameter was added. @@ -559,6 +564,27 @@ If the user would like to catch errors manually, the feature can be enabled by s .. versionadded:: 3.9 +suggest_on_error +^^^^^^^^^^^^^^^^ + +By default, when a user passes an invalid argument choice or subparser name, +:class:`ArgumentParser` will exit with error info and list the permissible +argument choices (if specified) or subparser names as part of the error message. + +If the user would like to enable suggestions for mistyped argument choices and +subparser names, the feature can be enabled by setting ``suggest_on_error`` to +``True``. Note that this only applies for arguments when the choices specified +are strings:: + + >>> parser = argparse.ArgumentParser(description='Process some integers.', suggest_on_error=True) + >>> parser.add_argument('--action', choices=['sum', 'max']) + >>> parser.add_argument('integers', metavar='N', type=int, nargs='+', + ... help='an integer for the accumulator') + >>> parser.parse_args(['--action', 'sumn', 1, 2, 3]) + tester.py: error: argument --action: invalid choice: 'sumn', maybe you meant 'sum'? (choose from 'sum', 'max') + +.. versionadded:: 3.14 + The add_argument() method ------------------------- diff --git a/Lib/argparse.py b/Lib/argparse.py index fa9f5211257e96..ece6f2e880d5cb 100644 --- a/Lib/argparse.py +++ b/Lib/argparse.py @@ -1773,6 +1773,8 @@ class ArgumentParser(_AttributeHolder, _ActionsContainer): - allow_abbrev -- Allow long options to be abbreviated unambiguously - exit_on_error -- Determines whether or not ArgumentParser exits with error info when an error occurs + - suggest_on_error - Enables suggestions for mistyped argument choices + and subparser names. (default: ``False``) """ def __init__(self, @@ -1788,7 +1790,8 @@ def __init__(self, conflict_handler='error', add_help=True, allow_abbrev=True, - exit_on_error=True): + exit_on_error=True, + suggest_on_error=False): superinit = super(ArgumentParser, self).__init__ superinit(description=description, @@ -1804,6 +1807,7 @@ def __init__(self, self.add_help = add_help self.allow_abbrev = allow_abbrev self.exit_on_error = exit_on_error + self.suggest_on_error = suggest_on_error add_group = self.add_argument_group self._positionals = add_group(_('positional arguments')) @@ -2601,14 +2605,27 @@ def _get_value(self, action, arg_string): def _check_value(self, action, value): # converted value must be one of the choices (if specified) choices = action.choices - if choices is not None: - if isinstance(choices, str): - choices = iter(choices) - if value not in choices: - args = {'value': str(value), - 'choices': ', '.join(map(str, action.choices))} - msg = _('invalid choice: %(value)r (choose from %(choices)s)') - raise ArgumentError(action, msg % args) + if choices is None: + return + + if isinstance(choices, str): + choices = iter(choices) + + if value not in choices: + args = {'value': str(value), + 'choices': ', '.join(map(str, action.choices))} + msg = _('invalid choice: %(value)r (choose from %(choices)s)') + + if self.suggest_on_error and isinstance(value, str): + if all(isinstance(choice, str) for choice in action.choices): + import difflib + suggestions = difflib.get_close_matches(value, action.choices, 1) + if suggestions: + args['closest'] = suggestions[0] + msg = _('invalid choice: %(value)r, maybe you meant %(closest)r? ' + '(choose from %(choices)s)') + + raise ArgumentError(action, msg % args) # ======================= # Help-formatting methods diff --git a/Lib/test/test_argparse.py b/Lib/test/test_argparse.py index 78692fd3474782..a3c096ef3199c8 100644 --- a/Lib/test/test_argparse.py +++ b/Lib/test/test_argparse.py @@ -2253,6 +2253,95 @@ class TestNegativeNumber(ParserTestCase): ('--complex -1e-3j', NS(int=None, float=None, complex=-0.001j)), ] +class TestArgumentAndSubparserSuggestions(TestCase): + """Test error handling and suggestion when a user makes a typo""" + + def test_wrong_argument_error_with_suggestions(self): + parser = ErrorRaisingArgumentParser(suggest_on_error=True) + parser.add_argument('foo', choices=['bar', 'baz']) + with self.assertRaises(ArgumentParserError) as excinfo: + parser.parse_args(('bazz',)) + self.assertIn( + "error: argument foo: invalid choice: 'bazz', maybe you meant 'baz'? (choose from bar, baz)", + excinfo.exception.stderr + ) + + def test_wrong_argument_error_no_suggestions(self): + parser = ErrorRaisingArgumentParser(suggest_on_error=False) + parser.add_argument('foo', choices=['bar', 'baz']) + with self.assertRaises(ArgumentParserError) as excinfo: + parser.parse_args(('bazz',)) + self.assertIn( + "error: argument foo: invalid choice: 'bazz' (choose from bar, baz)", + excinfo.exception.stderr, + ) + + def test_wrong_argument_subparsers_with_suggestions(self): + parser = ErrorRaisingArgumentParser(suggest_on_error=True) + subparsers = parser.add_subparsers(required=True) + subparsers.add_parser('foo') + subparsers.add_parser('bar') + with self.assertRaises(ArgumentParserError) as excinfo: + parser.parse_args(('baz',)) + self.assertIn( + "error: argument {foo,bar}: invalid choice: 'baz', maybe you meant" + " 'bar'? (choose from foo, bar)", + excinfo.exception.stderr, + ) + + def test_wrong_argument_subparsers_no_suggestions(self): + parser = ErrorRaisingArgumentParser(suggest_on_error=False) + subparsers = parser.add_subparsers(required=True) + subparsers.add_parser('foo') + subparsers.add_parser('bar') + with self.assertRaises(ArgumentParserError) as excinfo: + parser.parse_args(('baz',)) + self.assertIn( + "error: argument {foo,bar}: invalid choice: 'baz' (choose from foo, bar)", + excinfo.exception.stderr, + ) + + def test_wrong_argument_no_suggestion_implicit(self): + parser = ErrorRaisingArgumentParser() + parser.add_argument('foo', choices=['bar', 'baz']) + with self.assertRaises(ArgumentParserError) as excinfo: + parser.parse_args(('bazz',)) + self.assertIn( + "error: argument foo: invalid choice: 'bazz' (choose from bar, baz)", + excinfo.exception.stderr, + ) + + def test_suggestions_choices_empty(self): + parser = ErrorRaisingArgumentParser(suggest_on_error=True) + parser.add_argument('foo', choices=[]) + with self.assertRaises(ArgumentParserError) as excinfo: + parser.parse_args(('bazz',)) + self.assertIn( + "error: argument foo: invalid choice: 'bazz' (choose from )", + excinfo.exception.stderr, + ) + + def test_suggestions_choices_int(self): + parser = ErrorRaisingArgumentParser(suggest_on_error=True) + parser.add_argument('foo', choices=[1, 2]) + with self.assertRaises(ArgumentParserError) as excinfo: + parser.parse_args(('3',)) + self.assertIn( + "error: argument foo: invalid choice: '3' (choose from 1, 2)", + excinfo.exception.stderr, + ) + + def test_suggestions_choices_mixed_types(self): + parser = ErrorRaisingArgumentParser(suggest_on_error=True) + parser.add_argument('foo', choices=[1, '2']) + with self.assertRaises(ArgumentParserError) as excinfo: + parser.parse_args(('3',)) + self.assertIn( + "error: argument foo: invalid choice: '3' (choose from 1, 2)", + excinfo.exception.stderr, + ) + + class TestInvalidAction(TestCase): """Test invalid user defined Action""" @@ -2505,18 +2594,6 @@ def test_required_subparsers_no_destination_error(self): 'error: the following arguments are required: {foo,bar}\n$' ) - def test_wrong_argument_subparsers_no_destination_error(self): - parser = ErrorRaisingArgumentParser() - subparsers = parser.add_subparsers(required=True) - subparsers.add_parser('foo') - subparsers.add_parser('bar') - with self.assertRaises(ArgumentParserError) as excinfo: - parser.parse_args(('baz',)) - self.assertRegex( - excinfo.exception.stderr, - r"error: argument {foo,bar}: invalid choice: 'baz' \(choose from foo, bar\)\n$" - ) - def test_optional_subparsers(self): parser = ErrorRaisingArgumentParser() subparsers = parser.add_subparsers(dest='command', required=False) @@ -2862,7 +2939,7 @@ def test_single_parent_mutex(self): parser = ErrorRaisingArgumentParser(parents=[self.ab_mutex_parent]) self._test_mutex_ab(parser.parse_args) - def test_single_granparent_mutex(self): + def test_single_grandparent_mutex(self): parents = [self.ab_mutex_parent] parser = ErrorRaisingArgumentParser(add_help=False, parents=parents) parser = ErrorRaisingArgumentParser(parents=[parser]) diff --git a/Misc/NEWS.d/next/Library/2024-09-24-18-49-16.gh-issue-99749.gBDJX7.rst b/Misc/NEWS.d/next/Library/2024-09-24-18-49-16.gh-issue-99749.gBDJX7.rst new file mode 100644 index 00000000000000..3ecd75c5b551b6 --- /dev/null +++ b/Misc/NEWS.d/next/Library/2024-09-24-18-49-16.gh-issue-99749.gBDJX7.rst @@ -0,0 +1 @@ +Adds a feature to optionally enable suggestions for argument choices and subparser names if mistyped by the user.