On Tue, 27 Dec 2016, Tobias Pape wrote:

>
> On 25.12.2016, at 17:09, Levente Uzonyi <leves at caesar.elte.hu> wrote:
>
>> Hi All,
>> 
>> We had a discussion[1] about #species, in the context of Sets and IdentitySets, and its multiple roles which it cannot fulfill[2].
>> 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.
>> 
>> Example:
>> 
>> 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?

An OrderedCollection of course. #collect: would always return an 
OrderedCollection.

Levente

>
> Best regards
> 	-Tobias
>
>> 
>> 
>> Levente
>> 
>> [1] http://lists.squeakfoundation.org/pipermail/squeak-dev/2014-November/180766.html
>> [2] http://lists.squeakfoundation.org/pipermail/squeak-dev/2014-November/180809.html
>>