The Trunk: Collections-cmm.466.mcz

Chris Muller uploaded a new version of Collections to project The Trunk:
http://source.squeak.org/trunk/Collections-cmm.466.mcz

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

Name: Collections-cmm.466
Author: cmm
Time: 29 November 2011, 9:26:57.286 pm
UUID: 3a05d4e5-8c72-4b50-85a2-40eba66bc358
Ancestors: Collections-ul.465

Allow subclasses to override the internal 'array' of a HashedCollection.

=============== Diff against Collections-ul.465 ===============

Item was added:
+ ----- Method: HashedCollection class>>arrayType (in category 'private') -----
+ arrayType
+ ^ Array!

Item was changed:
  ----- Method: HashedCollection>>growTo: (in category 'private') -----
  growTo: anInteger
  "Grow the elements array and reinsert the old elements"
 
  | oldElements |
  oldElements := array.
+ array := self class arrayType new: anInteger.
- array := Array new: anInteger.
  self noCheckNoGrowFillFrom: oldElements!

Item was changed:
  ----- Method: HashedCollection>>initialize: (in category 'private') -----
  initialize: n
  "Initialize array to an array size of n"
+ array := self class arrayType new: n.
- array := Array new: n.
  tally := 0!

On Mon, 26 Dec 2011, [hidden email] wrote:

Why is #arrayType on the class side? What are the practical alternatives
of Array as #arrayType?


Levente

> Why is #arrayType on the class side?

I must admit I wrung my hands about this decision -- the answer is
"consistency" with OrderedCollection, which needs its #arrayType on
the class side for the case where the user wants to pre-allocate extra
slots.  In that case, the initial 'array' is allocated in the
class-side constructor (see OrderedCollection class>>#new:).

However, HashedCollection doesn't do it that way, so it probably
_could_ have gone on the instance-side.  Still, I thought there was no
harm in being consistent with OC.

> What are the practical alternatives of
> Array as #arrayType?

To have a compactable Array class.  WbArray is a subclass of Array
included with Magma that can, therefore, be used with the
WriteBarrier.  WbOrderedCollection, WbSet and WbDictionary follow by
simply overriding their #arrayType which, in at least the app I'm
measuring, affords a 20X improvement in application performance.

 - Chris

> To have a compactable Array class.  WbArray is a subclass of Array

s/compactable/uncompactable