Path: csiph.com!x330-a1.tempe.blueboxinc.net!aioe.org!eternal-september.org!feeder.eternal-september.org!.POSTED!not-for-mail
From: markspace <-@.>
Newsgroups: comp.lang.java.programmer
Subject: Re: Java puzzler
Date: Sun, 15 May 2011 05:40:15 -0700
Organization: A noiseless patient Spider
Lines: 32
Message-ID: <iqohjj$a0q$1@dont-email.me>
References: <4db69c13-878f-4806-adb2-a3c5adb1c48c@glegroupsg2000goo.googlegroups.com> <qrGdnWE1mOKFHVfQnZ2dnUVZ_uKdnZ2d@earthlink.com> <alpine.DEB.2.00.1105112141410.27211@urchin.earth.li> <I6SdnROEzeMni1bQnZ2dnUVZ_sKdnZ2d@earthlink.com> <alpine.DEB.2.00.1105122029030.7602@urchin.earth.li> <-8mdnSRPEIdA21HQnZ2dnUVZ_j2dnZ2d@earthlink.com> <iqhhim$blg$4@speranza.aioe.org> <iqhjks$798$1@dont-email.me> <AcCdnflMosQt-lHQnZ2dnUVZ_t2dnZ2d@earthlink.com> <iqhumi$750$1@dont-email.me> <jY-dnS9ZV4RyG1HQnZ2dnUVZ_tadnZ2d@earthlink.com> <alpine.DEB.2.00.1105140954470.12373@urchin.earth.li> <iqm848$52b$1@dont-email.me> <alpine.DEB.2.00.1105150033090.12373@urchin.earth.li> <iqnakv$t9g$1@dont-email.me> <alpine.DEB.2.00.1105151107130.12373@urchin.earth.li>
Mime-Version: 1.0
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
Injection-Date: Sun, 15 May 2011 12:40:20 +0000 (UTC)
Injection-Info: mx04.eternal-september.org; posting-host="Gyo0FQiuGFjMddvl0JJHxw"; logging-data="10266"; mail-complaints-to="abuse@eternal-september.org";	posting-account="U2FsdGVkX19MzszReL3VwoIYbw1nJ6aTA8e9u2UeMJw="
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.2.17) Gecko/20110414 Thunderbird/3.1.10
In-Reply-To: <alpine.DEB.2.00.1105151107130.12373@urchin.earth.li>
Cancel-Lock: sha1:WuayrVR8x5dSVQytENATUBaGltQ=
Xref: x330-a1.tempe.blueboxinc.net comp.lang.java.programmer:4113

On 5/15/2011 3:16 AM, Tom Anderson wrote:

> Fair enough. I suppose my position is that this hardware ability has to
> be used in the service of some solidly well-defined software semantics.
> Throwing exceptions at random from arithmetic expressions is not what i
> think of as solidly well-defined.


I guess I'm not understanding what people think is wrong with the 
semantics of "overflow."  Overflow is very well defined.  It's something 
like 8 gates on the hardware level, and happens at the same speed as the 
the add or subtract itself.  I.e., about 1 CPU cycle in most cases nowadays.

By contrast, the current semantics of integer math are that sometimes 
you get the right answer and sometimes you don't.  I consider that to be 
non-deterministic.

Here's a method to sum a list of numbers:

   public int sum( int[] nums ) {
     int sum = 0;
     for( int n : nums ) sum += n;
     return sum;
   }

What I want is for this to throw an error if it can't compute the sum 
correctly.  How is that non-semantic, even slightly?  How is the current 
implementation where sometimes this works and sometimes it doesn't even 
*slightly* semantic in comparison?