Allow tuples for metavars.

3 files changed, 61 insertions, 13 deletions

diff --git a/argparse.py b/argparse.py
index 8ee556b..fab54e3 100644
--- a/argparse.py
+++ b/argparse.py
@@ -495,7 +495,8 @@ class HelpFormatter(object):
 

     def _format_action_invocation(self, action):

         if not action.option_strings:

-            return self._format_metavar(action, action.dest)

+            metavar, = self._metavar_formatter(action, action.dest)(1)

+            return metavar

 

         else:

             parts = []

@@ -515,30 +516,36 @@ class HelpFormatter(object):
 

             return ', '.join(parts)

 

-    def _format_metavar(self, action, default_metavar):

+    def _metavar_formatter(self, action, default_metavar):

         if action.metavar is not None:

-            name = action.metavar

+            result = action.metavar

         elif action.choices is not None:

             choice_strs = [str(choice) for choice in action.choices]

-            name = '{%s}' % ','.join(choice_strs)

+            result = '{%s}' % ','.join(choice_strs)

         else:

-            name = default_metavar

-        return name

+            result = default_metavar

+        def format(tuple_size):

+            if isinstance(result, tuple):

+                return result

+            else:

+                return (result, ) * tuple_size

+        return format

 

     def _format_args(self, action, default_metavar):

-        name = self._format_metavar(action, default_metavar)

+        get_metavar = self._metavar_formatter(action, default_metavar)

         if action.nargs is None:

-            result = name

+            result = '%s' % get_metavar(1)

         elif action.nargs == OPTIONAL:

-            result = '[%s]' % name

+            result = '[%s]' % get_metavar(1)

         elif action.nargs == ZERO_OR_MORE:

-            result = '[%s [%s ...]]' % (name, name)

+            result = '[%s [%s ...]]' % get_metavar(2)

         elif action.nargs == ONE_OR_MORE:

-            result = '%s [%s ...]' % (name, name)

+            result = '%s [%s ...]' % get_metavar(2)

         elif action.nargs is PARSER:

-            result = '%s ...' % name

+            result = '%s ...' % get_metavar(1)

         else:

-            result = ' '.join([name] * action.nargs)

+            formats = ['%s' for _ in range(action.nargs)]

+            result = ' '.join(formats) % get_metavar(action.nargs)

         return result

 

     def _expand_help(self, action):

diff --git a/doc/source/add_argument.rst b/doc/source/add_argument.rst
index 667889f..43e1b29 100644
--- a/doc/source/add_argument.rst
+++ b/doc/source/add_argument.rst
@@ -378,6 +378,20 @@ If you would like to provide a different name for your argument in help messages
 

 Note that ``metavar`` only changes the *displayed* name - the name of the attribute on the :meth:`parse_args` object is still determined by the dest_ value.

 

+Different values of ``nargs`` may cause the metavar to be used multiple times.

+If you'd like to specify a different display name for each of the arguments, you can provide a tuple to ``metavar``::

+

+  >>> parser = argparse.ArgumentParser(prog='PROG')

+  >>> parser.add_argument('-x', nargs=2)

+  >>> parser.add_argument('--foo', nargs=2, metavar=('bar', 'baz'))

+  >>> parser.print_help()

+  usage: PROG [-h] [-x X X] [--foo bar baz]

+

+  optional arguments:

+    -h, --help     show this help message and exit

+    -x X X

+    --foo bar baz

+

 

 dest

 ----

diff --git a/test/test_argparse.py b/test/test_argparse.py
index 67026d9..bd5a854 100644
--- a/test/test_argparse.py
+++ b/test/test_argparse.py
@@ -3080,6 +3080,33 @@ class TestHelpNone(HelpTestCase):
     version = ''

 

 

+class TestHelpTupleMetavar(HelpTestCase):

+    """Test specifying metavar as a tuple"""

+

+    parser_signature = Sig(prog='PROG')

+    argument_signatures = [

+        Sig('-w', help='w', nargs='+', metavar=('W1', 'W2')),

+        Sig('-x', help='x', nargs='*', metavar=('X1', 'X2')),

+        Sig('-y', help='y', nargs=3, metavar=('Y1', 'Y2', 'Y3')),

+        Sig('-z', help='z', nargs='?', metavar=('Z1', )),

+    ]

+    argument_group_signatures = []

+    usage = '''\

+        usage: PROG [-h] [-w W1 [W2 ...]] [-x [X1 [X2 ...]]] [-y Y1 Y2 Y3] \

+[-z [Z1]]

+        '''

+    help = usage + '''\

+

+        optional arguments:

+          -h, --help        show this help message and exit

+          -w W1 [W2 ...]    w

+          -x [X1 [X2 ...]]  x

+          -y Y1 Y2 Y3       y

+          -z [Z1]           z

+        '''

+    version = ''

+

+

 class TestHelpRawText(HelpTestCase):

     """Test the RawTextHelpFormatter"""