From: lutz@iks-jena.de (Lutz Donnerhacke)
Subject: Re: Does a null pointer always raise Constraint_Error?
Date: 13 Dec 2000 14:25:42 GMT
Date: 2000-12-13T14:25:42+00:00 [thread overview]
Message-ID: <slrn93f1ic.vo.lutz@taranis.iks-jena.de> (raw)
In-Reply-To: IeLZ5.7495$bw.651358@news.flash.net
* Ken Garlington wrote:
>"Lutz Donnerhacke" <lutz@iks-jena.de> wrote in message
>: * Robert Dewar wrote:
>: [access to empty arrays represent as Null (System.Address)]
>: > subtype n is string (1 .. 0);
>: > type np is access n;
>: > a, b : np;
>: >
>: > if a.all = b.all then ...
>: >
>: >it is a common compiler bug to translate this as
>: >
>: > for j in n'range loop
>: > if a.all (j) = b.all (j) ....
>: >
>: >and the null loop causes no checks to be made :-)
>:
>: I do not see the bug.
>
>Probably explains why it's so common...
>
>(I'm guessing it might have something to do with the case where a or b are
>null. Presumably, no exception would be raised if the compiler generated
>this kind of code, due to n'range causing the body of the loop to be
>skipped altogether?)
Possible, but irrelevant IMHO. Two empty arrays of the same component type
are equal per definition.
--
http://www.tm.oneiros.de/calendar/2001/index.html
next prev parent reply other threads:[~2000-12-13 14:25 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
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[not found] ` <tgzoihpon4.fsf@mercury.rus.uni-stuttgart.de>
[not found] ` <9074fi$93b$1@nnrp1.deja.com>
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2000-12-12 16:23 ` Does a null pointer always raise Constraint_Error? Wayne Magor
2000-12-12 20:27 ` Keith Thompson
2000-12-13 0:46 ` Robert Dewar
2000-12-13 8:58 ` Lutz Donnerhacke
2000-12-13 13:56 ` Ken Garlington
2000-12-13 14:25 ` Lutz Donnerhacke [this message]
2000-12-13 14:58 ` Florian Weimer
2000-12-13 15:17 ` Lutz Donnerhacke
2000-12-13 15:40 ` Robert Dewar
2000-12-13 20:07 ` Florian Weimer
2000-12-14 13:08 ` Robert Dewar
2000-12-14 14:29 ` Ken Garlington
2000-12-15 1:45 ` Robert Dewar
2000-12-13 15:37 ` Robert Dewar
2000-12-12 20:31 ` Keith Thompson
2000-12-13 19:58 ` Florian Weimer
2000-12-13 0:43 ` Robert Dewar
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