On 07.08.2010, at 12:29, Bert Freudenberg wrote:

> 
> On 07.08.2010, at 05:56, Andreas Raab wrote:
> 
>> On 8/6/2010 6:20 PM, Igor Stasenko wrote:
>>> On 6 August 2010 17:45, Randal L. Schwartz<merlyn at stonehenge.com>  wrote:
>>>>>>>>> "Casey" == Casey Ransberger<casey.obrien.r at gmail.com>  writes:
>>>> 
>>>> Casey>  It's literally adding a method to make the cuneiform smalltalk
>>>> Casey>  crap accessible to new people, who are liable to search on terms
>>>> Casey>  like 'slice.'
>>>> 
>>>> What you are asking for is something that would be useful for only
>>>> those first few hours, and then be a maintenance clutter for the
>>>> remaining years of programming.
>>>> 
>>>> I vote "-1".
>>>> 
>>> +1 to your -1.
>> 
>> I vote -2 on your -1 which should leave us at +0 I think :-)=)
>> 
>> No, seriously. I think there's actually a pretty good and generic interpretation of slice if you consider it to be an operation that can collect arbitrary sequences. For example:
>> 
>> Collection>>slice: aCollection
>> 	"Slice the receiver by aCollection, collecting all elements
>> 	in the receiver that are keyed by aCollection."
>> 
>> 	^aCollection collect:[:each| self at: each] as: self species.
>> 
>> With a polymorphic implementation this would allow some interesting uses that are quite difficult to implement otherwise, for example:
>> 
>> 	dd := Dictionary newFromPairs: {
>> 		'firstName'. 'Joe'.
>> 		'lastName'. 'Sixpack'
>> 		'dob'. '01-01-2001'.
>> 		'zip'. '12345'
>> 	}.
>> 	dd slice: #(firstName lastName).
>> 
>> This would return a dictionary with only firstName and lastName. And of course, when used with intervals it would behave identical to #copyFrom:to: just somewhat less efficient, but that's offset by, say, uses such as:
>> 
>> 	"Slice out all the odd elements"
>> 	aCollection slice: (1 to: aCollection size by: 2).
>> 
>> Etc. So I think the argument for #slice: can be made and we should consider it as a more generic operation instead of just a slower version of #copyFrom:to:.
> 
> But we have that already. It's called #atAll: which is nicely consistent with the rest of the collection protocols. We just need to add a more generic version in Collection.
> 
> - Bert -

That said, having a Subsequence object like Travis mentioned would warrant adding a new protocol. I seem to remember seeing something like this in Squeak before (MappedCollection maybe?)

- Bert -