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From: Martin Gregorie <martin@address-in-sig.invalid>
Newsgroups: comp.lang.java.programmer
Subject: Re: [JLS] new long[0][ -1 ]
Date: Fri, 10 Jul 2015 20:19:23 +0000 (UTC)
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On Fri, 10 Jul 2015 14:19:24 +0000, Andreas Leitgeb wrote:

> Eric Sosman <esosman@comcast-dot-net.invalid> wrote:
>>      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 ...  :-)
> 
> Some class's constructor gets passed two ints meaning width and height
> of some rectangular grid. Currently, the only argument-sanitization is
> to create a two dimensional array with it. Any exceptions caused by bad
> arguments to "new int[ height ][ width ]" will be seen by client-code.
> 
> My concern was, that a negative width might pass undetected after a zero
> height.  As is now clear: it doesn't, so it's all fine for me.  I don't
> care what exceptions are thrown back for bogus arguments, as long as all
> bogosity ends in some exception right on the spot.
> 
>>      <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>
> 
> Too bad, arrays are fixed-size, so we cannot even add elements to make
> it zero-sized.  ;-)
>
Two features I'd have liked to see in Java are non-zero based arrays, e.g.
 int temperatureOcurrences[-40:55] and flexible array bounds, e.g
 int samples[0:flex]

Neither are new ideas, both dating from the '60s: Algol 60 had non-zero-
based fixed size arrays and Algol 68 implemented both concepts: both are 
useful in some circumstances as is multi-dimensional array slicing (Algol 
68 had that too).


-- 
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