asymertical behavior with where: and where:sortedBy:...

[Hilaire Fernandes]

I found an asymmetrical behaviour in recurrent use 
where:distinct:sortedBy:descending: compare to the use of recurrent where:

I get use to take a MagmaCollection and extract from it a small subset 
in a reader. Then I get the reader passed from one object to another one 
and eventually refined it with another where: message.

Being able to apply recursively where: query from one initial collection 
is very very handy.

As long as you do that with where: it is fined. You can repeat over and 
over where query with the same indexes of the initial collection.
However when applying with where:distinct:sortedBy:descending: then 
indexes of the initial collection are lost (expect the one used for the 
sort). It happens because the sort create a new MagmaCollection

I enclosed there a small fix. I expect it slows down a bit the sort 
because of the recreated indexes in the new collection.
In the other hand, asymmetrical behaviour is not great at all.
May be we should have a fast sort (what we have now) and slower sort but 
with the expected behaviour.

I am curious to read what Chris think about the issue.


Hilaire
-------------- next part --------------
'From Squeak3.9 of 26 December 2007 [latest update: #7068] on 4 April 2008 at 3:43:10 pm'!

!MagmaCollectionReader methodsFor: 'private' stamp: 'HilaireFernandes 4/4/2008 15:41'!
newReducedReaderOn: attribute makeDistinct: aBoolean 
	| newMc index |
	"index := self indexNamed: attribute."
	newMc := MagmaCollection new.
	"newMc addIndex: index."
	collection indexesDo: [:each | newMc addIndex: each].
	collection isNewCollection 
		ifTrue: 
			[aBoolean 
				ifTrue: [self asSet do: [:each | newMc add: each]]
				ifFalse: [self do: [:each | newMc add: each]]]
		ifFalse: 
			[collection 
				load: newMc
				from: self
				makeDistinct: aBoolean].
	^ newMc read: attribute! !