Yes, 0 is more sensible.
>From the outside that does not matter, because Integer is (or should be)
fully polymorphic to Fraction and we don't really care about internal
representation.
That's an implementation detail.
>From the inside, having all Fraction reduced is a valuable invariant: this
assumption enables some simplifications of various algorithms (less gcd:
computations etc...)
Un-reduced Fractions are rarely used now, only as an intermediate during
evaluation of (Integer op Fraction).
IMO, #zero is too general for answering such a Fraction that does not
respect the invariants.
It's the same as having:
   LargePositiveInteger>>zero
       ^self basicNew: self basicSize

Nicolas


2013/3/30 Frank Shearar <frank.shearar at gmail.com>

> No, just following ScaledDecimal's example. (0 / 1 is the simplest
> zero fraction.)
>
> But I'm not strongly in favour of what I wrote: if 0 (the integer) is
> a more sensible zero for Fraction, I'd be perfectly happy with
> removing it and so falling back to Number >> #zero. I'm much more
> interested in the protocol.
>
> frank
>
> On 30 March 2013 22:35, Nicolas Cellier
> <nicolas.cellier.aka.nice at gmail.com> wrote:
> > I wonder about the Fraction implementation.
> > Since any Integer isFraction I think it's better to simply let super ^0.
> > Synthetizing an unreduced Fraction should be restricted to very specific
> > case. Do you have such specific usage?
> >
> > Nicolas
> >
> >
> > 2013/3/30 <commits at source.squeak.org>
> >
> >> Frank Shearar uploaded a new version of Kernel to project The Trunk:
> >> http://source.squeak.org/trunk/Kernel-fbs.752.mcz
> >>
> >> ==================== Summary ====================
> >>
> >> Name: Kernel-fbs.752
> >> Author: fbs
> >> Time: 30 March 2013, 10:09:47.906 pm
> >> UUID: 0724a0a2-6b96-4e07-94ed-79bdc4e2466b
> >> Ancestors: Kernel-eem.751
> >>
> >> Increase the "polymorphitude" of numbers by supplying a default
> >> implementation of #zero, together with a few per-type specialisations
> to go
> >> with those we already have.
> >>
> >> =============== Diff against Kernel-eem.751 ===============
> >>
> >> Item was added:
> >> + ----- Method: Float class>>zero (in category 'constants') -----
> >> + zero
> >> +       ^ 0.0.!
> >>
> >> Item was added:
> >> + ----- Method: Fraction class>>zero (in category 'constants') -----
> >> + zero
> >> +       ^ self numerator: 0 denominator: 1.!
> >>
> >> Item was added:
> >> + ----- Method: Number class>>zero (in category 'constants') -----
> >> + zero
> >> +       ^ 0.!
> >>
> >>
> >
> >
> >
> >
>
>
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