merge heads
diff --git a/Lib/string.py b/Lib/string.py
index b57c79b..72a09f7 100644
--- a/Lib/string.py
+++ b/Lib/string.py
@@ -169,7 +169,8 @@
self.check_unused_args(used_args, args, kwargs)
return result
- def _vformat(self, format_string, args, kwargs, used_args, recursion_depth):
+ def _vformat(self, format_string, args, kwargs, used_args, recursion_depth,
+ auto_arg_index=0):
if recursion_depth < 0:
raise ValueError('Max string recursion exceeded')
result = []
@@ -185,6 +186,23 @@
# this is some markup, find the object and do
# the formatting
+ # handle arg indexing when empty field_names are given.
+ if field_name == '':
+ if auto_arg_index is False:
+ raise ValueError('cannot switch from manual field '
+ 'specification to automatic field '
+ 'numbering')
+ field_name = str(auto_arg_index)
+ auto_arg_index += 1
+ elif field_name.isdigit():
+ if auto_arg_index:
+ raise ValueError('cannot switch from manual field '
+ 'specification to automatic field '
+ 'numbering')
+ # disable auto arg incrementing, if it gets
+ # used later on, then an exception will be raised
+ auto_arg_index = False
+
# given the field_name, find the object it references
# and the argument it came from
obj, arg_used = self.get_field(field_name, args, kwargs)
@@ -195,7 +213,8 @@
# expand the format spec, if needed
format_spec = self._vformat(format_spec, args, kwargs,
- used_args, recursion_depth-1)
+ used_args, recursion_depth-1,
+ auto_arg_index=auto_arg_index)
# format the object and append to the result
result.append(self.format_field(obj, format_spec))
diff --git a/Lib/test/test_string.py b/Lib/test/test_string.py
index c2bdfdb..3e65071 100644
--- a/Lib/test/test_string.py
+++ b/Lib/test/test_string.py
@@ -32,6 +32,23 @@
self.assertEqual(fmt.format("foo{0}", "bar"), "foobar")
self.assertEqual(fmt.format("foo{1}{0}-{1}", "bar", 6), "foo6bar-6")
+ def test_auto_numbering(self):
+ fmt = string.Formatter()
+ self.assertEqual(fmt.format('foo{}{}', 'bar', 6),
+ 'foo{}{}'.format('bar', 6))
+ self.assertEqual(fmt.format('foo{1}{num}{1}', None, 'bar', num=6),
+ 'foo{1}{num}{1}'.format(None, 'bar', num=6))
+ self.assertEqual(fmt.format('{:^{}}', 'bar', 6),
+ '{:^{}}'.format('bar', 6))
+ self.assertEqual(fmt.format('{:^{pad}}{}', 'foo', 'bar', pad=6),
+ '{:^{pad}}{}'.format('foo', 'bar', pad=6))
+
+ with self.assertRaises(ValueError):
+ fmt.format('foo{1}{}', 'bar', 6)
+
+ with self.assertRaises(ValueError):
+ fmt.format('foo{}{1}', 'bar', 6)
+
def test_conversion_specifiers(self):
fmt = string.Formatter()
self.assertEqual(fmt.format("-{arg!r}-", arg='test'), "-'test'-")
diff --git a/Misc/NEWS b/Misc/NEWS
index 09c0f40..6f2a8c8 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -30,6 +30,10 @@
- Issue #12546: Allow \x00 to be used as a fill character when using str, int,
float, and complex __format__ methods.
+- Issue #13598: Modify string.Formatter to support auto-numbering of
+ replacement fields. It now matches the behavior of str.format() in
+ this regard.
+
Library
-------