i would make an #identityCollect: for sets.
so it is more explicit, and also can be used with any other sets as input.

On 26 November 2014 at 22:56, Eliot Miranda <eliot.miranda at gmail.com> wrote:

>
>
> On Wed, Nov 26, 2014 at 1:26 PM, Levente Uzonyi <leves at elte.hu> wrote:
>
>> On Wed, 26 Nov 2014, David T. Lewis wrote:
>>
>>  On Wed, Nov 26, 2014 at 08:01:49PM +0100, Levente Uzonyi wrote:
>>>
>>>> On Wed, 26 Nov 2014, Eliot Miranda wrote:
>>>>
>>>>  Hi All,
>>>>> ? ? IdentitySet>>collect: answers a Set, not an IdentitySet.? Anyone
>>>>> else
>>>>> agree this is a serious bug?? Anyone else disagree?
>>>>>
>>>>> WTF??
>>>>>
>>>>> (IdentitySet withAll: #(1 2 3 1.0 2.0 3.0)) collect: [:e| e] a Set(1.0
>>>>> 2 3)
>>>>> --
>>>>> best,Eliot
>>>>>
>>>>>
>>>> Sometimes it's feasable to return an IdentitySet, other times it's not,
>>>> so
>>>> there's no optimal solution - #collect: can't cover all cases.
>>>>
>>>> Set >> #collect: explicitly returns a Set, because this is the least bad
>>>> solution to handle all of its subclasses reasonably well.
>>>> In case of WeakSet, returning a WeakSet makes no sense, because some of
>>>> your objects will disappear immediately.
>>>> In case of IdentitySet, PluggableSet, KeyedSet and KeyedIdentitySet the
>>>> returned values may not behave well in the original collection.
>>>>
>>>> The best is to always be explicit:
>>>>
>>>> (IdentitySet withAll: #(1 2 3 1.0 2.0 3.0)) collect: [ :e | e ] as:
>>>> IdentitySet
>>>> "==> an IdentitySet(1 2 3 1.0 2.0 3.0)"
>>>>
>>>> Levente
>>>>
>>>>
>>> In Squeak 2.8 (checked on http://bertfreudenberg.github.io/SqueakJS/run/
>>> ):
>>>
>>>  (IdentitySet withAll: #(1 2 3 1.0 2.0 3.0)) collect: [:e| e] ==> a
>>> Set(2.0 1 2 3 3.0 1.0)
>>>
>>>
>>> But in trunk I get this:
>>>
>>>  (IdentitySet withAll: #(1 2 3 1.0 2.0 3.0)) collect: [:e| e] ==> a
>>> Set(1 2 3)
>>>
>>>
>>> So answering a Set makes sense for the reasons that Levente explains,
>>> but trunk
>>> is definitely broken WRT the contents of that set.
>>>
>>> This bug needs a unit test to go along with whatever fix we agree on.
>>>
>>
>> It's not a bug either. The Floats are not there, because they are equal
>> to the integers:
>>
>> 1 = 1.0 "==> true"
>> 1.0 = 1 "==> true"
>>
>> Therefore they have the same hash:
>>
>> 1 hash "==> 1"
>> 1.0 hash "==> 1"
>>
>> The bug was in Squeak 2.8:
>> 1.0 = 1 "==> true"
>> 1 = 1.0 "==> true"
>> 1 hash "==> 1"
>> 1.0 hash "==> 61440"
>>
>> Here's the comment of Float >> hash from The Trunk:
>>         "Hash is reimplemented because = is implemented. Both words of
>> the float are used. (The bitShift:'s ensure that the intermediate results
>> do not become a large integer.) Care is taken to answer same hash as an
>> equal Integer."
>>
>
> Exactly.
>
> My hope would be something like this (Set order is arbitrary)
>
>         ((IdentitySet withAll: #(1 2 3 1.0 2.0 3.0)) collect: [:e| e]) =>
> IdentitySet (1 2 3 1.0 2.0 3.0)
>
> but that
>        (Set withAll: #(1 2 3 1.0 2.0 3.0)) => Set (1 2 3)
>
> (and it always contains just the integers since these are added first).
>
> But Levente's collect:as: solution is perfectly acceptable and as he
> points out has the advantage of being explicit.
>
>
>> Levente
>>
>>
>>> Dave
>>>
>>>
>>>
>>>
>>
>
>
> --
> best,
> Eliot
>
>
>
>


-- 
Best regards,
Igor Stasenko.
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