[squeak-dev] #species vs OrderedColleciton
Das.Linux at gmx.de
Tue Dec 27 16:36:32 UTC 2016
On 25.12.2016, at 17:09, Levente Uzonyi <leves at caesar.elte.hu> wrote:
> Hi All,
> We had a discussion about #species, in the context of Sets and IdentitySets, and its multiple roles which it cannot fulfill.
> A similar issue arises in case of OrderedCollection and its subclasses, but with a smoother resolution, because an OrderedCollection is always an acceptable result (for #collect:).
> So, I suggest we should change OrderedCollection >> #collect: to always return an OrderedCollection. This change obviously would not affect OrderedCollection, but we already have the same override in SortedCollection.
> Currently the following raises and error:
> (FloatCollection withAll: #(1 2 3)) collect: #asString
> Of course, #collect:as: works as expected:
> (FloatCollection withAll: #(1 2 3)) collect: #asString as: OrderedCollection
> "==> an OrderedCollection('1.0' '2.0' '3.0')"
> So, why not make #collect: behave the same way?
> This change would make #species not being used in #collect:, which is similar to the solution we have in Set and subclasses.
> Currently #select: and #copyEmpty also use #species, but no class implements #species in the hierarchy. So, changing #species to return OrderedCollection would have unwanted side effects. (This also shows that #species doesn't solve anything here.)
> Any objections?
Just a question for clarification, would
(FloatCollection withAll: #(1.0 2.0 3.0)) collect: [:ea | ea sqrt]
result in a FloatCollection or in an OrderedCollection?
>  http://lists.squeakfoundation.org/pipermail/squeak-dev/2014-November/180766.html
>  http://lists.squeakfoundation.org/pipermail/squeak-dev/2014-November/180809.html
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