Hello, Ok, I read all the mails. I see your point about not cancelling the possibility to use #to:by: on any Number. However, the remark from David Grandi seems really relevant to me. You can NOT write anything else than a *rational number* when writing a literal using the XXX.XXX pattern. I think it would be legit to generate scaled decimal by default from float literals and to be able to get Float only by either explicitly specify it (#asFloat, etcâ¦) or because of computation that lead to a Float (e.g. the need to approach an irrational number ?). I would be curious to see the impact of such change in the compiler on the system. Maybe a first step is indeed to implement a rule in Renraku to encourage people to use ScaledDecimals. Cheers, Julien --- Julien Delplanque Doctorant à lâUniversité de Lille http://juliendelplanque.be/phd.html Equipe Rmod, Inria Bâtiment B 40, Avenue Halley 59650 Villeneuve d'Ascq Numéro de téléphone: +333 59 35 86 40
Le 19 sept. 2018 à 09:22, Davide Grandi <grndvd63m06f704u@gmail.com> a écrit :
0.0 to: 1.0 by: 0.1 Receiver and arguments, lexically (the dot), are float BUT are written as decimal number (zero, one, one tenth).
I think that in a text you can ONLY write "decimal" numbers or (in bases other than 10 [or with factors other than 2^x and 5 ?]), at worst, repeating decimals (eg 0,1 in base 3 = 1/3 ~ 0.333...), that are ultimately fractions.
So, may be, if the receiver or an argument is a float the compiler may issue a warning and compile to non-float, if receiver or arguments are computed ... there should be a default behaviour.
Best regards,
Davide Grandi (PS : I work mainly in an ERP that has only integers ... and doubles)
On 18/09/2018 11:52, Guillaume Larcheveque wrote:
Maybe #to:by: should convert its parameters in Fraction to avoid Floats problems (not sure, just an idea)
2018-09-18 11:25 GMT+02:00 Esteban Lorenzano <estebanlm@gmail.com <mailto:estebanlm@gmail.com>>:
On 18 Sep 2018, at 11:13, Guillermo Polito <guillermopolito@gmail.com <mailto: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
-- Guillaume Larcheveque