# HG changeset patch
# Parent 6d278f426417063b12703f980cb17411849b6326
Allow arguments to be added to mulitple mutually exclusive groups

diff -r 6d278f426417 Doc/library/argparse.rst
--- a/Doc/library/argparse.rst	Fri Jul 05 18:05:29 2013 -1000
+++ b/Doc/library/argparse.rst	Sat Jul 06 16:03:35 2013 +0200
@@ -1728,6 +1728,28 @@
      usage: PROG [-h] (--foo | --bar)
      PROG: error: one of the arguments --foo --bar is required
 
+   Finally, you can also add existing arguments to a mutually exclusive
+   group. This allows you to include arguments in more than one mutually
+   exclusive group::
+
+     >>> import argparse
+     >>> parser = argparse.ArgumentParser(prog='PROG')
+     >>> foo_arg = parser.add_argument('--foo', action='store_true')
+     >>> bar_arg = parser.add_argument('--bar', action='store_false')
+     >>> baz_arg = parser.add_argument('--baz', action='store_true')
+     >>> group = parser.add_mutually_exclusive_group(foo_arg, bar_arg, required=True)
+     >>> group = parser.add_mutually_exclusive_group(foo_arg, baz_arg, required=True)
+     >>> parser.parse_args(["--bar", "--baz"])
+     Namespace(bar=False, baz=True, foo=False)
+     >>> parser.parse_args(["--foo"])
+     Namespace(bar=False, baz=False, foo=True)
+     >>> parser.parse_args(["--foo", "--bar"])
+     usage: PROG [-h] (--foo | --bar) [--baz]
+     PROG: error: argument --bar: not allowed with argument --foo
+     >>> parser.parse_args(["--foo", "--baz"])
+     usage: PROG [-h] (--foo | --bar) [--baz]
+     PROG: error: argument --baz: not allowed with argument --foo
+
    Note that currently mutually exclusive argument groups do not support the
    *title* and *description* arguments of
    :meth:`~ArgumentParser.add_argument_group`.
diff -r 6d278f426417 Lib/argparse.py
--- a/Lib/argparse.py	Fri Jul 05 18:05:29 2013 -1000
+++ b/Lib/argparse.py	Sat Jul 06 16:03:35 2013 +0200
@@ -1339,9 +1339,11 @@
         self._action_groups.append(group)
         return group
 
-    def add_mutually_exclusive_group(self, **kwargs):
+    def add_mutually_exclusive_group(self, *args, **kwargs):
         group = _MutuallyExclusiveGroup(self, **kwargs)
         self._mutually_exclusive_groups.append(group)
+        for action in args:
+            group._group_actions.append(action)
         return group
 
     def _add_action(self, action):
diff -r 6d278f426417 Lib/test/test_argparse.py
--- a/Lib/test/test_argparse.py	Fri Jul 05 18:05:29 2013 -1000
+++ b/Lib/test/test_argparse.py	Sat Jul 06 16:03:35 2013 +0200
@@ -2689,6 +2689,42 @@
           -c          c help
         '''
 
+class TestMutuallyExclusiveGroupWithExistingArguments(MEMixin, TestCase):
+
+    def get_parser(self, required):
+        parser = ErrorRaisingArgumentParser(prog='PROG')
+        a_action = parser.add_argument('-a', action='store_true', help='a help')
+        b_action = parser.add_argument('-b', action='store_true', help='b help')
+        c_action = parser.add_argument('-c', action='store_true', help='c help')
+        d_action = parser.add_argument('-d', action='store_true', help='d help')
+        parser.add_mutually_exclusive_group(a_action, c_action, required=required)
+        parser.add_mutually_exclusive_group(a_action, d_action, required=required)
+        return parser
+
+    failures = ['-a -c', '-a -d', '-a -c -d', '-a -b -c', '-a -b -d', '-a -b -c -d']
+    successes = [
+        ('-a -b', NS(a=True, b=True, c=False, d=False)),
+        ('-c -d', NS(a=False, b=False, c=True, d=True)),
+        ('-c -b -d', NS(a=False, b=True, c=True, d=True)),
+    ]
+    successes_when_not_required = [
+        ('', NS(a=False, b=False, c=False, d=False)),
+        ('-b', NS(a=False, b=True, c=False, d=False)),
+    ]
+
+    usage_when_required = usage_when_not_required = '''\
+        usage: PROG [-h] [-a] [-b] [-c] [-d]
+        '''
+    help = '''\
+
+        optional arguments:
+          -h, --help  show this help message and exit
+          -a          a help
+          -b          b help
+          -c          c help
+          -d          d help
+        '''
+
 # =================================================
 # Mutually exclusive group in parent parser tests
 # =================================================