[Python-3000] [Python-3000-checkins] r60376 - in python/branches/py3k: Lib/test/test_float.py Lib/test/test_long.py Objects/stringlib/formatter.h

[Eric Smith]

Guido van Rossum wrote:
> On Jan 27, 2008 8:16 PM, Nick Coghlan <ncoghlan at gmail.com> wrote:
>> eric.smith wrote:
>>> Author: eric.smith
>>> Date: Sun Jan 27 22:07:59 2008
>>> New Revision: 60376
>>>
>>> Modified:
>>>    python/branches/py3k/Lib/test/test_float.py
>>>    python/branches/py3k/Lib/test/test_long.py
>>>    python/branches/py3k/Objects/stringlib/formatter.h
>>> Log:
>>> Restrict format presentation types to those specified in the 'Standard Format Specifiers' section of PEP 3101.
>> I think this checkin goes too far in removing support for the floating
>> point formatting codes from integers. Guido objected to %d working on
>> floats last year, but expected %f and friends to continue to work on
>> integers [1]. This makes sense when you consider that there is no data
>> loss in displaying an integer as a floating point number, while there is
>> a definite potential for data loss when going the other way.
>>
>> Perhaps the PEP needs a tweak (referencing Guido's email) to state
>> explicitly that the builtin integers understand the floating point
>> formatting codes, but the builtin and standard library floating point
>> types don't understand the integer codes? That area of the PEP is
>> slightly problematic anyway where it suggests that integers could handle
>> the floating point codes by delegating to float() - that isn't quite
>> true, since the maximum precision on floats is less than the maximum
>> precision on integers.
>>
>> Cheers,
>> Nick.
>>
>> [1]
>> http://mail.python.org/pipermail/python-3000/2007-August/009066.html
> 
> Agreed with Nick -- in general, the idea is that ints should be
> allowed whenever floats are expected -- just not the other way around!
> Python 2.x broke this in one important place, division -- 2/3 and
> 2.0/3.0 had different meanings there. We are fixing this in 3.0.
> Please maintain this rule for formatting!
> 

Okay, I'll restore ints understanding float formatting codes.