GH-99749: Add optional feature to suggest correct names (ArgumentParser) (GH-124456)

1 files changed, 26 insertions, 9 deletions

diff --git a/Lib/argparse.py b/Lib/argparse.py
index fa9f521..ece6f2e 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 @@ class ArgumentParser(_AttributeHolder, _ActionsContainer):
                  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 @@ class ArgumentParser(_AttributeHolder, _ActionsContainer):
         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 @@ class ArgumentParser(_AttributeHolder, _ActionsContainer):
     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