On Mon, Oct 29, 2018 at 12:47 PM Nicolas Cellier <
nicolas.cellier.aka.nice at gmail.com> wrote:

>
>
> Le lun. 29 oct. 2018 à 08:33, Eliot Miranda <eliot.miranda at gmail.com> a
> écrit :
>
>> Hi Chris,
>>
>> On Sun, Oct 28, 2018 at 5:13 PM <commits at source.squeak.org> wrote:
>>
>>> Chris Cunningham uploaded a new version of CollectionsTests to project
>>> The Inbox:
>>> http://source.squeak.org/inbox/CollectionsTests-cbc.296.mcz
>>>
>>> ==================== Summary ====================
>>>
>>> Name: CollectionsTests-cbc.296
>>> Author: cbc
>>> Time: 28 October 2018, 5:12:30.875512 pm
>>> UUID: 12a1d6bf-85c7-8d40-aa1c-022556c1cb18
>>> Ancestors: CollectionsTests-topa.295
>>>
>>> Test for #hash and #= bugs.  In anticipation of fixing these.
>>>
>>> =============== Diff against CollectionsTests-topa.295 ===============
>>>
>>> Item was added:
>>> + ----- Method: IntervalTest>>testHashBug3380 (in category 'tests') -----
>>> + testHashBug3380
>>> +       "Array and Interval equate, but their hashes didn't.  Test that
>>> this is fixed.
>>> +       It is about mantis bug http://bugs.squeak.org/view.php?id=6455"
>>> +       | interval array |
>>> +       interval := (1 to: 3).
>>> +       array:= #(1 2 3).
>>> +       self assert: interval equals: array.
>>>
>>
>> At least for me I don't see why this should be true.  We have
>> hasEqualElements: for this, so
>>
>> SequenceableCollection allSubclasses select:
>> [:c|
>> [(#(1 2 3) as: c) = #(1 2 3)] on: Error do: [:ex| false]]
>> an OrderedCollection(LinkedList Interval RunArray Array Mutex WeakArray
>> Monitor)
>>
>> SequenceableCollection allSubclasses reject:
>> [:c|
>> [(#(1 2 3) as: c) = #(1 2 3)] on: Error do: [:ex| true]] an
>> OrderedCollection(OrderedCollection SourceFileArray SoundBuffer WordArray
>> ShortIntegerArray Bitmap FloatArray ShortRunArray ByteArray IntegerArray
>> SparseLargeTable PredicatedArray DoubleByteArray DoubleWordArray Semaphore
>> SortedCollection GraphicSymbol UrlArgumentList TraitComposition
>> ObjectFinalizerCollection WeakOrderedCollection StandardSourceFileArray
>> ExpandedSourceFileArray WordArrayForSegment ActionSequence
>> WeakActionSequence Cubic KedamaFloatArray SocketAddress SparseLargeArray
>> FloatCollection WeakActionSequenceTrappingErrors)
>>
>> SequenceableCollection allSubclasses reject:
>> [:c|
>> [(#(1 2 3) as: c) hasEqualElements: #(1 2 3)] on: Error do: [:ex| true]]
>> an OrderedCollection(SoundBuffer ShortIntegerArray)
>>
>> i.e. there are many SequenceableCollection subclasses, including
>> OrderedCollection, and all the integer arrays (ByteArray through
>> DoubleWordArray) that are not #= to an equivalent integer array.
>>
>> I would throw out the assumption that intervals and arrays are equal; as
>> long as hasEqualElements: answers true things are good, no?
>>
> +1
>
> If = is based on species, we might have to revise =...
>

So, I was doing a straight forward reading of bug 3380 (
http://bugs.squeak.org/view.php?id=3380 ) where it was talking about
falling back to the super slow hashing.

Based on your comments and Eliot's comments, I think I should backtrack
from that position - especially now that Interval is no longer the same
species as Array.

Still, that problem exists as noted in 3380; it is still the fact that (1
to: 3) = #( 1 2 3 ), but the hashes are different.  This is because (among
other things) the hash for collections uses species while #= doesn't.

Using Eliot's formula:

(SequenceableCollection allSubclasses select:
[:c|
[(#(1 2 3) as: c) = #(1 2 3)] on: Error do: [:ex| true]] )
difference:
(SequenceableCollection allSubclasses select:
[:c|
[(#(1 2 3) as: c) hash = #(1 2 3) hash] on: Error do: [:ex| true]]  )
 an OrderedCollection(Interval RunArray TextLineInterval)

So, Interval, RunArray, and TextLineInterval have collection issues with
Array.
But, given that 26 subclasses of SequenceableCollection pass this test, we
don't want to change #= to be species aware.  So, how to fix without
breaking other goodness?  Or, just leave 3380 open for later inspection?

In any case, I'll revert to a much simpler Interval>>hash (called
#hashBetter in the other thread)

-cbc

>
>> +       self assert: interval hash equals: array hash.!
>>>
>>> Item was added:
>>> + ----- Method: IntervalTest>>testHashEqualIfIntervalEqual (in category
>>> 'tests') -----
>>> + testHashEqualIfIntervalEqual
>>> +       | interval1 interval2 |
>>> +       interval1 := 0 to: 1.
>>> +       interval2 := 0 to: 5/3. "Taken from an actual issue in an image"
>>> +       self assert: interval1 equals: interval2.
>>> +       self assert: interval1 hash equals: interval2 hash.!
>>>
>>>
>>>
>>
>> --
>> _,,,^..^,,,_
>> best, Eliot
>>
>>
>
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