New submission from Akima: 1 / 0 (where both numbers are decimal.Decimal) produces a decimal.DivisionByZero exception as I would expect. This is useful. I can use a simple try except block to catch a potential division by zero error in my code.
0 / 0 (where both numbers are decimal.Decimal) produces a decimal.InvalidOperation exception. This is undesirable. I would expect another decimal.DivisionByZero exception. This means that if I want to catch a division by zero error in my code using a try except block, I now have to catch exceptions for both decimal.DivisionByZero and decimal.InvalidOperation. Presumably decimal.InvalidOperation can be raised in other scenarios, so catching it may result in masking a programming fault (which isn't just a division by zero: 0 / 0). If you perform the same division but using standard Python integers instead of decimal.Decimal objects, the behaviour is exactly as you would expect: 0 / 0 and 1 / 0 both produce a ZeroDivisionError exception. I have tested this in CPython 3.3.5, 3.2.3 and 2.7.3. All versions produce the same behaviour. Demonstration: Python 2.7.3 (default, Feb 27 2014, 19:58:35) [GCC 4.6.3] on linux2 Type "help", "copyright", "credits" or "license" for more information. >>> from decimal import Decimal as d >>> d(1) / d(0) Traceback (most recent call last): File "<stdin>", line 1, in <module> File "/usr/lib/python2.7/decimal.py", line 1323, in __truediv__ return context._raise_error(DivisionByZero, 'x / 0', sign) File "/usr/lib/python2.7/decimal.py", line 3866, in _raise_error raise error(explanation) decimal.DivisionByZero: x / 0 >>> d(0) / d(0) Traceback (most recent call last): File "<stdin>", line 1, in <module> File "/usr/lib/python2.7/decimal.py", line 1322, in __truediv__ return context._raise_error(DivisionUndefined, '0 / 0') File "/usr/lib/python2.7/decimal.py", line 3866, in _raise_error raise error(explanation) decimal.InvalidOperation: 0 / 0 >>> 1 / 0 Traceback (most recent call last): File "<stdin>", line 1, in <module> ZeroDivisionError: integer division or modulo by zero >>> 0 / 0 Traceback (most recent call last): File "<stdin>", line 1, in <module> ZeroDivisionError: integer division or modulo by zero >>> Here is the same demonstration but using a Python 3.2.3 interpreter: Python 3.2.3 (default, Feb 27 2014, 21:31:18) [GCC 4.6.3] on linux2 Type "help", "copyright", "credits" or "license" for more information. >>> from decimal import Decimal as d >>> d(1) / d(0) Traceback (most recent call last): File "<stdin>", line 1, in <module> File "/usr/lib/python3.2/decimal.py", line 1300, in __truediv__ return context._raise_error(DivisionByZero, 'x / 0', sign) File "/usr/lib/python3.2/decimal.py", line 3926, in _raise_error raise error(explanation) decimal.DivisionByZero: x / 0 >>> d(0) / d(0) Traceback (most recent call last): File "<stdin>", line 1, in <module> File "/usr/lib/python3.2/decimal.py", line 1299, in __truediv__ return context._raise_error(DivisionUndefined, '0 / 0') File "/usr/lib/python3.2/decimal.py", line 3926, in _raise_error raise error(explanation) decimal.InvalidOperation: 0 / 0 >>> 1 / 0 Traceback (most recent call last): File "<stdin>", line 1, in <module> ZeroDivisionError: division by zero >>> 0 / 0 Traceback (most recent call last): File "<stdin>", line 1, in <module> ZeroDivisionError: division by zero >>> ---------- messages: 226125 nosy: akima priority: normal severity: normal status: open title: Inconsistent division by 0 behaviour in decimal module type: behavior versions: Python 2.7, Python 3.2, Python 3.3 _______________________________________ Python tracker <rep...@bugs.python.org> <http://bugs.python.org/issue22306> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com