[Python-Dev] Decimal & amp; lt; -& amp; gt; float comparisons in py3k.

Guido van Rossum guido at python.org
Sun Mar 21 18:07:56 CET 2010


On Sat, Mar 20, 2010 at 11:59 PM, Nick Coghlan <ncoghlan at gmail.com> wrote:
> Greg Ewing wrote:
>> Nick Coghlan wrote:
>>
>>> Note that Antoine's point was that float("0.1") and
>>> Decimal.from_float(0.1) should compare equal.
>>
>> That would mean that Decimal("0.1") != float("0.1"), which might be
>> surprising to someone who didn't realise they were mixing floats
>> and decimals.
>
> That's fine - binary floats *are* surprising. That's why Decimal exists
> in the first place.

Decimals can be just as surprising:

>>> Decimal(1) / Decimal(3) * Decimal(3) == Decimal(1)
False
>>>


-- 
--Guido van Rossum (python.org/~guido)


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