[Python-Dev] PEP 327: Decimal Data Type

[Stephen Horne]

On Fri, 30 Jan 2004 07:06:21 -0800, Michael Chermside
<mcherm at mcherm.com> wrote:

>Facundo Batista writes:
>> I'm proud to announce that the PEP for Decimal Data Type is now published 
>>         http://www.python.org/peps/pep-0327.html 
>
>VERY nice work here.
>
>Here's my 2 cents:
>
>    (1) You propose conversion from floats via:
>      Decimal(1.1, 2) == Decimal('1.1')
>      Decimal(1.1, 16) == Decimal('1.1000000000000001')
>      Decimal(1.1) == Decimal('110000000000000008881784197001252...e-51')
>
>        I think that we'd do even better to ommit the second use. People who 
>really want to convert floats exactly can easily write "Decimal(1.1, 60)". But 
>hardly anyone wants to convert floats exactly, while lots of newbies would 
>forget to include the second parameter. I'd say just make Decimal(someFloat) 
>raise a TypeError with a helpful message about how you need that second 
>parameter when using floats.

Good point. A 'DecimalExact' or similar function could perhaps be
provided to replace the simple conversion when people have really
thought about it and do really want it.


-- 
Steve Horne

steve at ninereeds dot fsnet dot co dot uk