On 18 Sep 2018, at 11:13, Guillermo Polito <guillermopolito@gmail.com> wrote:
On Tue, Sep 18, 2018 at 11:06 AM Julien <julien.delplanque@inria.fr <mailto:julien.delplanque@inria.fr>> wrote: Hello,
I realised that it is possible to create an interval of floats.
I think this is bad because, since intervals are computed by successively adding a number, it might result in precision errors.
(0.0 to: 1.0 by: 0.1) asArray >>> #(0.0 0.1 0.2 0.30000000000000004 0.4 0.5 0.6000000000000001 0.7000000000000001 0.8 0.9 1.0)
The correct (precise) way to do it would be to use ScaledDecimal:
(0.0s1 to: 1.0s1 by: 0.1s1) asArray >>> #(0.0s1 0.1s1 0.2s1 0.3s1 0.4s1 0.5s1 0.6s1 0.7s1 0.8s1 0.9s1 1.0s1)
I opened an issue about it: https://pharo.fogbugz.com/f/cases/22467/Float-should-not-implement-to-to-by-... <https://pharo.fogbugz.com/f/cases/22467/Float-should-not-implement-to-to-by-...>
And Iâd like to discuss this with you.
What do you think?
Well, I think it's a matter of balance :)
#to:by: is defined in Number. So we could, for example, cancel it in Float. However, people would still be able to do
1 to: 1.0 by: 0.1
Which would still show problems.
Nevertheless, I have seen this a lot of times. 0.0 to: 1.0 by: 0.1 Is a common use case.
And moreover, we could try to do
1 to: 7 by: (Margin fromNumber: 1)
And even worse
1 to: Object new by: (Margin fromNumber: 1)
I think adding type-validations all over the place is not a good solution, and is kind of opposite to our philosophy...
So we should - document the good usages - document the bad ones - and live with the fact that we have a relaxed type system that will fail at runtime :)
yup. But not cancel. Esteban
Guille