[Python-checkins] cpython (merge 3.2 -> default): Merge #11131

[mark.dickinson]

http://hg.python.org/cpython/rev/af0dcd9df0c0
changeset:   68397:af0dcd9df0c0
parent:      68393:3680692b54eb
parent:      68396:426057570bee
user:        Mark Dickinson <mdickinson at enthought.com>
date:        Sat Mar 12 11:18:46 2011 +0000
summary:
  Merge #11131

files:
  Misc/NEWS

diff --git a/Lib/decimal.py b/Lib/decimal.py
--- a/Lib/decimal.py
+++ b/Lib/decimal.py
@@ -1045,14 +1045,16 @@
             if ans:
                 return ans
 
-        if not self:
-            # -Decimal('0') is Decimal('0'), not Decimal('-0')
+        if context is None:
+            context = getcontext()
+
+        if not self and context.rounding != ROUND_FLOOR:
+            # -Decimal('0') is Decimal('0'), not Decimal('-0'), except
+            # in ROUND_FLOOR rounding mode.
             ans = self.copy_abs()
         else:
             ans = self.copy_negate()
 
-        if context is None:
-            context = getcontext()
         return ans._fix(context)
 
     def __pos__(self, context=None):
@@ -1065,14 +1067,15 @@
             if ans:
                 return ans
 
-        if not self:
-            # + (-0) = 0
+        if context is None:
+            context = getcontext()
+
+        if not self and context.rounding != ROUND_FLOOR:
+            # + (-0) = 0, except in ROUND_FLOOR rounding mode.
             ans = self.copy_abs()
         else:
             ans = Decimal(self)
 
-        if context is None:
-            context = getcontext()
         return ans._fix(context)
 
     def __abs__(self, round=True, context=None):
diff --git a/Lib/test/decimaltestdata/extra.decTest b/Lib/test/decimaltestdata/extra.decTest
--- a/Lib/test/decimaltestdata/extra.decTest
+++ b/Lib/test/decimaltestdata/extra.decTest
@@ -2745,3 +2745,73 @@
 pwmx438 power 18 1728 1729 -> 1
 pwmx439 power 19 1728 1729 -> 456
 pwmx440 power 20 1728 1729 -> 1
+
+-- plus and minus zero in various rounding modes (see issue 11131)
+extended: 1
+precision: 9
+maxexponent: 384
+minexponent: -383
+
+rounding: half_even
+plux1000 plus 0.0 -> 0.0
+plux1001 plus -0.0 -> 0.0
+minx1000 minus 0.0 -> 0.0
+minx1001 minus -0.0 -> 0.0
+absx1000 abs 0.0 -> 0.0
+absx1001 abs -0.0 -> 0.0
+
+rounding: half_up
+plux1010 plus 0.0 -> 0.0
+minx1010 minus 0.0 -> 0.0
+plux1011 plus -0.0 -> 0.0
+minx1011 minus -0.0 -> 0.0
+absx1010 abs 0.0 -> 0.0
+absx1011 abs -0.0 -> 0.0
+
+rounding: ceiling
+plux1020 plus 0.0 -> 0.0
+minx1020 minus 0.0 -> 0.0
+plux1021 plus -0.0 -> 0.0
+minx1021 minus -0.0 -> 0.0
+absx1020 abs 0.0 -> 0.0
+absx1021 abs -0.0 -> 0.0
+
+rounding: floor
+plux1030 plus 0.0 -> 0.0
+minx1030 minus 0.0 -> -0.0
+plux1031 plus -0.0 -> -0.0
+minx1031 minus -0.0 -> 0.0
+absx1030 abs 0.0 -> 0.0
+absx1031 abs -0.0 -> 0.0
+
+rounding: down
+plux1040 plus 0.0 -> 0.0
+minx1040 minus 0.0 -> 0.0
+plux1041 plus -0.0 -> 0.0
+minx1041 minus -0.0 -> 0.0
+absx1040 abs 0.0 -> 0.0
+absx1041 abs -0.0 -> 0.0
+
+rounding: up
+plux1050 plus 0.0 -> 0.0
+minx1050 minus 0.0 -> 0.0
+plux1051 plus -0.0 -> 0.0
+minx1051 minus -0.0 -> 0.0
+absx1050 abs 0.0 -> 0.0
+absx1051 abs -0.0 -> 0.0
+
+rounding: half_down
+plux1060 plus 0.0 -> 0.0
+minx1060 minus 0.0 -> 0.0
+plux1061 plus -0.0 -> 0.0
+minx1061 minus -0.0 -> 0.0
+absx1060 abs 0.0 -> 0.0
+absx1061 abs -0.0 -> 0.0
+
+rounding: 05up
+plux1070 plus 0.0 -> 0.0
+minx1070 minus 0.0 -> 0.0
+plux1071 plus -0.0 -> 0.0
+minx1071 minus -0.0 -> 0.0
+absx1070 abs 0.0 -> 0.0
+absx1071 abs -0.0 -> 0.0
diff --git a/Misc/NEWS b/Misc/NEWS
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -62,6 +62,9 @@
 Library
 -------
 
+- Issue #11131: Fix sign of zero in decimal.Decimal plus and minus
+  operations when the rounding mode is ROUND_FLOOR.
+
 - Issue #9935: Speed up pickling of instances of user-defined classes.
 
 - Issue #5622: Fix curses.wrapper to raise correct exception if curses

-- 
Repository URL: http://hg.python.org/cpython