I disagree. size implemented in terms of do: is quite appropriate. The subclass responsibility is do:. If this doesn't suit SequenceableCollection then size should be implemented as a subclass responsibility in SequenceableCollection, /not/ in Collection.

On Fri, Sep 30, 2011 at 1:12 PM, commits@source.squeak.org wrote:

A new version of Collections was added to project The Inbox: http://source.squeak.org/inbox/Collections-nice.423.mcz

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

Name: Collections-nice.423 Author: nice Time: 30 September 2011, 10:12:20.333 pm UUID: 7613573f-6d08-9d4c-9d9e-2eaacff799fe Ancestors: Collections-ul.422

#size and #do: default implementation will cause an infinite loop in every new subclass of SequenceableCollection without any form of warning to the poor programmer.

It's simple to avoid this bad behavior by:

• moving Collection>>size implementation to the sole place where it is used

(LinkedList)

• replacing it with a subclassResponsibility.

=============== Diff against Collections-ul.422 ===============

Item was changed: ----- Method: Collection>>size (in category 'accessing') ----- size "Answer how many elements the receiver contains."

•   ^self subclassResponsibility!
  

•   | tally |
  

•   tally := 0.
  

•   self do: [:each | tally := tally + 1].
  

•   ^ tally!
  
  

Item was added:

• ----- Method: LinkedList>>size (in category 'accessing') -----
• size

•   "Answer how many elements the receiver contains."
  

•   | tally |
  

•   tally := 0.
  

•   self do: [:each | tally := tally + 1].
  

•   ^ tally!