Issue #6857: Fix Decimal formatting to be consistent with existing float

formatting:  both are now right-aligned by default.

Lib/decimal.py

@@ -5497,7 +5497,10 @@ def _parse_format_specifier(format_spec, _localeconv=None):
             raise ValueError("Alignment conflicts with '0' in "
                              "format specifier: " + format_spec)
     format_dict['fill'] = fill or ' '
-    format_dict['align'] = align or '<'
+    # PEP 3101 originally specified that the default alignment should
+    # be left;  it was later agreed that right-aligned makes more sense
+    # for numeric types.  See http://bugs.python.org/issue6857.
+    format_dict['align'] = align or '>'
 
     # default sign handling: '-' for negative, '' for positive
     if format_dict['sign'] is None:

Lib/test/test_decimal.py

@@ -712,6 +712,7 @@ class DecimalFormatTest(unittest.TestCase):
             ('', '1.00', '1.00'),
 
             # test alignment and padding
+            ('6', '123', '   123'),
             ('<6', '123', '123   '),
             ('>6', '123', '   123'),
             ('^6', '123', ' 123  '),
@@ -741,7 +742,7 @@ class DecimalFormatTest(unittest.TestCase):
             (',', '-1234567', '-1,234,567'),
             (',', '-123456', '-123,456'),
             ('7,', '123456', '123,456'),
-            ('8,', '123456', '123,456 '),
+            ('8,', '123456', ' 123,456'),
             ('08,', '123456', '0,123,456'), # special case: extra 0 needed
             ('+08,', '123456', '+123,456'), # but not if there's a sign
             (' 08,', '123456', ' 123,456'),

Misc/NEWS

@@ -366,6 +366,9 @@ Core and Builtins
 Library
 -------
 
+- Issue #6857: Default format() alignment should be '>' for Decimal
+  instances.
+
 - Issue #6795: int(Decimal('nan')) now raises ValueError instead of
   returning NaN or raising InvalidContext.  Also, fix infinite recursion
   in long(Decimal('nan')).