Dividing decimals yields invalid results in Python 2.5 to 2.7

Question

After a very thorough read of the Python\'s decimal module documentation, I still find myself puzzled by what happens when I divide a decimal.

In Python 2.4.6 (makes

Answer 1

From your MacPorts bug, you have installed Xcode 4 and your version of Python 2.7.2 was built with the clang C compiler, rather than gcc-4.2. There is at least one known problem with building with clang on OS X that has been fixed in Python subsequent to the 2.7.2. release. Either apply the patch or, better, ensure the build uses gcc-4.2. Something like (untested!):

sudo bash
export CC=/usr/bin/gcc-4.2
port clean python27
port upgrade --force python27

prior to the build might work if MacPorts doesn't override it.

UPDATE: The required patch has now been applied to the MacPorts port files for Python 2. See https://trac.macports.org/changeset/87442

Answer 2

Just for the record: For python 2.7.3 compiled with clang (via Homebrew on OS X), this seems to be fixed.

Python 2.7.3 (default, Oct 10 2012, 13:00:00) 
[GCC 4.2.1 Compatible Apple Clang 4.1 ((tags/Apple/clang-421.11.66))] on darwin
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>>> import decimal
>>> decimal.Decimal(1000) / 10
Decimal('100')