Even more efficient might be to:  rather than flattening the
collection, another possible solution might be to employ Brent
Pinkney's Medley collection in the first place, which treats
collections embedded into collections as one flat collection without
ever needing to flatten them.

Attached, just in case you're interested.

  - Chris


On Mon, Aug 20, 2012 at 10:54 AM, Frank Shearar <frank.shearar at gmail.com> wrote:
> On 20 August 2012 16:51,  <commits at source.squeak.org> wrote:
>> Frank Shearar uploaded a new version of Collections to project The Inbox:
>> http://source.squeak.org/inbox/Collections-fbs.489.mcz
>>
>> ==================== Summary ====================
>>
>> Name: Collections-fbs.489
>> Author: fbs
>> Time: 20 August 2012, 4:51:36.018 pm
>> UUID: d1834809-65b5-46c0-9b26-fea7ec04a946
>> Ancestors: Collections-ul.488
>>
>> SequenceableCollection >> flatten turns a nested SequenceableCollection - a collection of collections of ... -  into a simple collection. Thus, #(1 (2 3) (4)) flatten = #(1 2 3 4).
>>
>> =============== Diff against Collections-ul.488 ===============
>>
>> Item was added:
>> + ----- Method: SequenceableCollection>>flatten (in category 'copying') -----
>> + flatten
>> +       | recur stream |
>> +       stream := WriteStream on: (Array new: self size). "A lower bound on the final stream count."
>> +       recur := [:coll | coll
>> +               do: [:each |
>> +                       each isCollection
>> +                               ifTrue: [recur value: each]
>> +                               ifFalse: [stream nextPut: each]]].
>> +       recur value: self.
>> +       ^ stream contents.!
>
> I've had to implement this a few times now, so I thought it time to
> offer it up for general consumption. My original implementation was
> recursive, using #collect: and #inject:into:. This of course used a
> lot of #copy sends. Using a WriteStream seems more efficient, both in
> time trials and in looking at MessageTally outputs (where GC usage was
> a fraction of the recursive implementation, and 40% of CPU time was
> actually spent in primitives).
>
> frank
>
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