(aSortFunction value: x value: y) returns a Boolean;

(aSortFunction value: x value: x) returns true.

So you can already set up a SortedCollection using

a SortFunction.�� So yes, that would work.

But there is no reason why #reversed (or my preference,

#converse) could not work on sortBlocks.

On 25 April 2018 at 23:27, Denis Kudriashov <dionisiydk@gmail.com> wrote:

Hi Richard.

I agree with your proposal.��

But it force me to think that we should completely move to SortFunction's.��

In that case SortCollection will have sortFunction variable instead of sortBlock. And for your scenario reverse operation will be simple expression: "sortFunction := sortFunction reversed".

2018-04-23 3:09 GMT+02:00 Richard O'Keefe <raoknz@gmail.com>:

Test case:

���� #(1 2 4) asSortedCollection reverse add: 3; yourself

<print it>

The answer *should* be aSortedCollection(4 3 2 1)

but *is* aSortedCollection(4 2 1 3).

This works in Squeak.

The problem is that SortedCollection does not define

#reverse[d] but simply inherits it(them), and the

inherited code pays no attention to the sortBlock.

I propose adding the following two methods to

SortedCollection:

reverseInPlace
������ |a z|
������ a := firstIndex.
������ z := lastIndex.
������ [a < z] whileTrue: [array swap: a with: z. a := a + 1. z := z - 1].
������ sortBlock := sortBlock
������ ������ ifNil: [[:x :y | y <= x]]
������ ������ ifNotNil: [[:x :y | sortBlock value: y value: x]].
������ ^self

reversed
������ ^self copy reverseInPlace

The ANSI method is #reverse, not #reversed, but Pharo

defines #reverse to call #reversed, and OrderedCollection overrides #reversed, so SortedCollection *must* override #reversed.

#reverseInPlace is the name Squeak uses for the other

method.�� It also has a definition in SequenceableCollection, which is not but is

equivalent to

reverseInPlace
������ |a z|
������ a := 1.
������ z := self size.
������ [a < z] whileTrue: [self swap: a with: z. a := a + 1. z := z - 1].l
������ ^self

r