[Python-Dev] range objects in 3.x

[Guido van Rossum]

On Fri, Sep 23, 2011 at 7:13 PM, Steven D'Aprano <steve at pearwood.info> wrote:
>>> http://code.activestate.com/recipes/577068-floating-point-range/
>>
>> I notice that your examples carefully skirt around the rounding issues.
>
> I also carefully *didn't* claim that it made rounding issues disappear
> completely. I'll add a note clarifying that rounding still occurs and as a
> consequence results can be unexpected.

I believe this API is fundamentally wrong for float ranges, even if
it's great for int ranges, and I will fight against adding it to the
stdlib in that form.

Maybe we can come up with a better API, and e.g. specify begin and end
points and the number of subdivisions? E.g. frange(0.0, 2.1, 3) would
generate [0.0, 0.7, 1.4]. Or maybe it would even be better to use
inclusive end points? OTOH if you consider extending the API to
complex numbers, it might be better to specify an initial value, a
step, and a count. So frange(0.0, 0.7, 3) to generate [0.0, 0.7, 1.4].
Probably it shouldn't be called frange then.

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