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Re: [JLS] new long[0][ -1 ]

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On 7/10/2015 8:58 AM, Andreas Leitgeb wrote:
> Eric Sosman <esosman@comcast-dot-net.invalid> wrote:
>> On 7/10/2015 7:52 AM, Andreas Leitgeb wrote:
>>> I've had a look at the JLS to find out about the more or less special
>>> case of a 2-dimensional array, whose first(outer) dimension is 0, but
>>> I didn't find any extra mention of that case.
>>>
>>>   From what I read, it would evaluate *all* the dimensions, then check
>>> if any of them is negative.
>>>
>>> But if first dimension is 0, then the loop shown in the "equivalent as"-
>>> code sample would not get its body run even once, so actually it wouldn't
>>> even notice if any of the further dimensions was negative.
>>>
>>> What would be an accurate *purely JLS-based* prediction for
>>>     new long[0][-1]
>>> (not caring about actual existing JVM implementations) ?
>>
>>       Intriguing question, but easily answered. 15.10.2, second
>> bullet, second sub-bullet:
>>
>> 	"Next, the values of the dimension expressions are checked.
>> 	If the value of any DimExpr expression is less than zero,
>> 	then a NegativeArraySizeException is thrown."
>
> My mistake was to generalize the first example in 15.10.1-2 .
>
> On second thought, the equivalence in the example-block is correct.
> It just cannot be generalized from dimensions 3,3 to "any" (like 0,-1),
> as for dims 0,-1 the compact form has to throw a NASE, while the
> alternative code doesn't.
>
> Thanks.  Knot in my brain dissolved. :-)

     You're welcome.  But contemplating the uses of an array with
fewer than zero elements has tied what remains of my brain in a
knot that may not dissolve until my brain itself does ...  :-)

     <off-topic> What use might we make of a minus-sized array?
Perhaps it could model the old joke about a biologist, an engineer,
and a mathematician at a sidewalk cafe.  They see two people enter a
building across the street, and a little later three people emerge.
"They have reproduced," says the biologist. "Observational error,"
says the engineer. And the mathematician observes "If somebody now
goes inside, the building will be empty." </off-topic>

-- 
esosman@comcast-dot-net.invalid
"Don't be afraid of work. Make work afraid of you." -- TLM

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[JLS] new long[0][ -1 ] Andreas Leitgeb <avl@auth.logic.tuwien.ac.at> - 2015-07-10 11:52 +0000
  Re: [JLS] new long[0][ -1 ] Eric Sosman <esosman@comcast-dot-net.invalid> - 2015-07-10 08:02 -0400
    Re: [JLS] new long[0][ -1 ] Andreas Leitgeb <avl@auth.logic.tuwien.ac.at> - 2015-07-10 12:58 +0000
      Re: [JLS] new long[0][ -1 ] Eric Sosman <esosman@comcast-dot-net.invalid> - 2015-07-10 09:45 -0400
        Re: [JLS] new long[0][ -1 ] Andreas Leitgeb <avl@auth.logic.tuwien.ac.at> - 2015-07-10 14:19 +0000
          Re: [JLS] new long[0][ -1 ] Martin Gregorie <martin@address-in-sig.invalid> - 2015-07-10 20:19 +0000
            Re: [JLS] new long[0][ -1 ] Eric Sosman <esosman@comcast-dot-net.invalid> - 2015-07-10 16:43 -0400
              Re: [JLS] new long[0][ -1 ] Martin Gregorie <martin@address-in-sig.invalid> - 2015-07-10 22:24 +0000
                Re: [JLS] new long[0][ -1 ] Eric Sosman <esosman@comcast-dot-net.invalid> - 2015-07-11 07:33 -0400
            Re: [JLS] new long[0][ -1 ] Andreas Leitgeb <avl@auth.logic.tuwien.ac.at> - 2015-07-10 21:17 +0000
              Re: [JLS] new long[0][ -1 ] Martin Gregorie <martin@address-in-sig.invalid> - 2015-07-10 22:29 +0000
            Re: [JLS] new long[0][ -1 ] Arne Vajhøj <arne@vajhoej.dk> - 2015-07-27 22:10 -0400
              Re: [JLS] new long[0][ -1 ] leif.roar@dimnakorr.com - 2015-07-28 01:53 -0500
                Re: [JLS] new long[0][ -1 ] Arne Vajhøj <arne@vajhoej.dk> - 2015-07-28 19:13 -0400
                Re: [JLS] new long[0][ -1 ] leif.roar@dimnakorr.com - 2015-07-28 21:50 -0500
              Re: [JLS] new long[0][ -1 ] Martin Gregorie <martin@address-in-sig.invalid> - 2015-07-28 11:13 +0000
                Re: [JLS] new long[0][ -1 ] Arne Vajhøj <arne@vajhoej.dk> - 2015-07-31 19:41 -0400
                Re: [JLS] new long[0][ -1 ] Martin Gregorie <martin@address-in-sig.invalid> - 2015-08-01 10:23 +0000
  Re: [JLS] new long[0][ -1 ] Joerg Meier <joergmmeier@arcor.de> - 2015-07-10 17:07 +0200
    Re: [JLS] new long[0][ -1 ] Andreas Leitgeb <avl@auth.logic.tuwien.ac.at> - 2015-07-10 18:10 +0000

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