2016-02-27 16:36 GMT+01:00 Rein, Patrick Patrick.Rein@hpi.de:

Oh! Cool. :)

Well then the only proposition I have is adding it to the abstract collection class as iterating over combinations is not specific to a sequenceable collection. Or am I missing something here?

Yes, you are right, but current implementation rely on indexing from 1 to self size... Generalization is trivial if we tolerate storing subcollections in an Array even if we iterate on a Set, ^self asArray combinations: n atATimeDo: aBlock If we insist on storing subcollections in self species, that may require a greater effort.

------------------------------ *Von:* squeak-dev-bounces@lists.squeakfoundation.org < squeak-dev-bounces@lists.squeakfoundation.org> im Auftrag von Nicolas Cellier nicolas.cellier.aka.nice@gmail.com *Gesendet:* Freitag, 26. Februar 2016 19:31 *An:* The general-purpose Squeak developers list *Betreff:* Re: [squeak-dev] The Inbox: Collections-pre.679.mcz

But this already exist, at least for SequenceableCollection, try:

(1 to: 4) combinations: 2 atATimeDo: [:e | Transcript cr; show: e printString]

2016-02-26 16:05 GMT+01:00 commits@source.squeak.org:

A new version of Collections was added to project The Inbox: http://source.squeak.org/inbox/Collections-pre.679.mcz

==================== Summary ====================

Name: Collections-pre.679 Author: pre Time: 26 February 2016, 4:04:56.205127 pm UUID: 2ac5821c-d6f5-418c-ab07-ed3c2b9de62c Ancestors: Collections-eem.678

This is a new iteration method which allows the iteration over asymmetric pairs. I have found this useful in game collision detections or duplicate detections. Alternatively we might want to take a second collection as input and create asymmetric pairs from self and this second collection.

=============== Diff against Collections-eem.678 ===============

Item was added:

• ----- Method: Collection>>asymmetricPairsDo: (in category 'accessing')

---

• asymmetricPairsDo: aBlock

•   | iterationCollection currentElement |
  

•   iterationCollection := self copy.
  

•   [currentElement := iterationCollection anyOne.
  

•   iterationCollection remove: currentElement.
  

•   iterationCollection isEmpty not]
  

•           whileTrue: [ iterationCollection
  

•                   do: [:element | aBlock value: currentElement
  

value: element]].!