Issue #7048: logb should round its result when that result doesn't fit

into the available precision.  (Tests for this change are included in
the most recent set of testcases from the Decimal Specification site;
those testcases will be updated shortly.)

diff --git a/Lib/decimal.py b/Lib/decimal.py
index 4d1f7f9f152a3495c677ea134d7db267b87f1358..75e5eea7b970312bbcbc77425317b6edf633f98a 100644 (file)
--- a/Lib/decimal.py
+++ b/Lib/decimal.py
@@ -3126,7 +3126,8 @@ class Decimal(object):
         # otherwise, simply return the adjusted exponent of self, as a
         # Decimal.  Note that no attempt is made to fit the result
         # into the current context.
-        return Decimal(self.adjusted())
+        ans = Decimal(self.adjusted())
+        return ans._fix(context)
 
     def _islogical(self):
         """Return True if self is a logical operand.

diff --git a/Misc/NEWS b/Misc/NEWS
index f90c8f4fa7d10ac34a3756dbacfea98781e329f8..cbd3040126e71f7ab80485dd5bd85c3dd6c34956 100644 (file)
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -398,6 +398,9 @@ Core and Builtins
 Library
 -------
 
+- Issue #7048: Force Decimal.logb to round its result when that result
+  is too large to fit in the current precision.
+
 - Issue #6516: Added owner/group support when creating tar archives in 
   Distutils.