From 0c626aade1b2c0f18ee37916b015fa9eaf93a925 Mon Sep 17 00:00:00 2001
From: Thomas Waldmann <tw AT waldmann-edv DOT de>
Date: Mon, 15 Dec 2014 18:48:37 +0100
Subject: added aliases support, thanks to Roland Kammerer

---
 argparse.py           | 17 ++++++++++++++---
 test/test_argparse.py | 51 +++++++++++++++++++++++++++++++++++++++++++++++++--
 2 files changed, 63 insertions(+), 5 deletions(-)

diff --git a/argparse.py b/argparse.py
index 681d19d..5a68b70 100644
--- a/argparse.py
+++ b/argparse.py
@@ -1050,9 +1050,13 @@ class _SubParsersAction(Action):
 
     class _ChoicesPseudoAction(Action):
 
-        def __init__(self, name, help):
+        def __init__(self, name, aliases, help):
+            metavar = dest = name
+            if aliases:
+                metavar += ' (%s)' % ', '.join(aliases)
             sup = super(_SubParsersAction._ChoicesPseudoAction, self)
-            sup.__init__(option_strings=[], dest=name, help=help)
+            sup.__init__(option_strings=[], dest=dest, help=help,
+                        metavar=metavar)
 
     def __init__(self,
                  option_strings,
@@ -1080,15 +1084,22 @@ class _SubParsersAction(Action):
         if kwargs.get('prog') is None:
             kwargs['prog'] = '%s %s' % (self._prog_prefix, name)
 
+        aliases = kwargs.pop('aliases', ())
+
         # create a pseudo-action to hold the choice help
         if 'help' in kwargs:
             help = kwargs.pop('help')
-            choice_action = self._ChoicesPseudoAction(name, help)
+            choice_action = self._ChoicesPseudoAction(name, aliases, help)
             self._choices_actions.append(choice_action)
 
         # create the parser and add it to the map
         parser = self._parser_class(**kwargs)
         self._name_parser_map[name] = parser
+
+        # make parser available under aliases also
+        for alias in aliases:
+            self._name_parser_map[alias] = parser
+
         return parser
 
     def _get_subactions(self):
diff --git a/test/test_argparse.py b/test/test_argparse.py
index 89284ad..4eb4581 100644
--- a/test/test_argparse.py
+++ b/test/test_argparse.py
@@ -1754,7 +1754,8 @@ class TestAddSubparsers(TestCase):
     def assertArgumentParserError(self, *args, **kwargs):
         self.assertRaises(ArgumentParserError, *args, **kwargs)
 
-    def _get_parser(self, subparser_help=False, prefix_chars=None):
+    def _get_parser(self, subparser_help=False, prefix_chars=None,
+                    aliases=False):
         # create a parser with a subparsers argument
         if prefix_chars:
             parser = ErrorRaisingArgumentParser(
@@ -1770,13 +1771,21 @@ class TestAddSubparsers(TestCase):
             'bar', type=float, help='bar help')
 
         # check that only one subparsers argument can be added
-        subparsers = parser.add_subparsers(help='command help')
+        subparsers_kwargs = {}
+        if aliases:
+            subparsers_kwargs['metavar'] = 'COMMAND'
+            subparsers_kwargs['title'] = 'commands'
+        else:
+            subparsers_kwargs['help'] = 'command help'
+        subparsers = parser.add_subparsers(**subparsers_kwargs)
         self.assertArgumentParserError(parser.add_subparsers)
 
         # add first sub-parser
         parser1_kwargs = dict(description='1 description')
         if subparser_help:
             parser1_kwargs['help'] = '1 help'
+        if aliases:
+            parser1_kwargs['aliases'] = ['1alias1', '1alias2']
         parser1 = subparsers.add_parser('1', **parser1_kwargs)
         parser1.add_argument('-w', type=int, help='w help')
         parser1.add_argument('x', choices='abc', help='x help')
@@ -1993,6 +2002,44 @@ class TestAddSubparsers(TestCase):
               -y {1,2,3}  y help
             '''))
 
+    def test_alias_invocation(self):
+        parser = self._get_parser(aliases=True)
+        self.assertEqual(
+            parser.parse_known_args('0.5 1alias1 b'.split()),
+            (NS(foo=False, bar=0.5, w=None, x='b'), []),
+        )
+        self.assertEqual(
+            parser.parse_known_args('0.5 1alias2 b'.split()),
+            (NS(foo=False, bar=0.5, w=None, x='b'), []),
+        )
+
+    def test_error_alias_invocation(self):
+        parser = self._get_parser(aliases=True)
+        self.assertArgumentParserError(parser.parse_args,
+                                       '0.5 1alias3 b'.split())
+
+    def test_alias_help(self):
+        parser = self._get_parser(aliases=True, subparser_help=True)
+        self.maxDiff = None
+        self.assertEqual(parser.format_help(), textwrap.dedent("""\
+            usage: PROG [-h] [--foo] bar COMMAND ...
+
+            main description
+
+            positional arguments:
+              bar                   bar help
+
+            optional arguments:
+              -h, --help            show this help message and exit
+              --foo                 foo help
+
+            commands:
+              COMMAND
+                1 (1alias1, 1alias2)
+                                    1 help
+                2                   2 help
+            """))
+
 # ============
 # Groups tests
 # ============
-- 
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