2009/10/24 Andres Valloud <[email protected]>:
> (furthermore, changing Interval>>hash to match that of Array in cases
> like (1 to: SmallInteger minVal) is bound to cause unacceptable
> performance penalties)
>
Yes, large Array hash has severe performance penalty anyway.
Maybe we shall not hash each and every element.
And, even forgetting about equality with Array, Inteval>>#= and
Interval>>#hash do not agree in Squeak and Pharo:
(1 to: 10 by: 5) = (1 to: 9 by: 5). -> true
(1 to: 10 by: 5) hash = (1 to: 9 by: 5) hash. -> false
Nicolas
> Andres Valloud wrote:
>> I'd rather make the interval not equal to the array, at least with the
>> message #=. Probably that can't be done safely. If that's the case,
>> I'd say the best approach is to leave it "broken" but documented in
>> terms of "some collections may compare 'reasonably', however, since
>> equality in those cases is not well defined, then the rule a = b => a
>> hash = b hash may be waived". For example, sure, #(1 2 3) = (1 to: 3),
>> however you can't do (1 to: 3) at: 2 put: 5. And 1.0 may be equal to 1,
>> but the numbers represent completely different things so even though the
>> numeric value is the same, equality is ill defined, and so it's not
>> necessary for the hashing rule to apply.
>>
>> Nicolas Cellier wrote:
>>
>>> http://bugs.squeak.org/view.php?id=3380
>>> http://bugs.squeak.org/view.php?id=3488
>>>
>>> 2009/10/24 Andrew P. Black <[email protected]>:
>>>
>>>
>>>> The golden rule of hashing is (a = b) => (a hash = b hash). Right?
>>>>
>>>> Look at this:
>>>>
>>>> (1 to: 10) species ---> Array
>>>> #(1 2 3 4 5 6 7 8 9 10) species ---> Array
>>>>
>>>> (1 to: 10) = #(1 2 3 4 5 6 7 8 9 10) ---> true
>>>>
>>>> However,
>>>>
>>>> (1 to: 10) hash = #(1 2 3 4 5 6 7 8 9 10) hash ---> false.
>>>>
>>>> I believe that the last is a bug.
>>>>
>>>> Andrew
>>>>
>>>>
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