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Date: Tue, 6 Jul 2010 11:20:49 +0200
From: Gilles Sadowski <gilles@harfang.homelinux.org>
To: dev@commons.apache.org
Subject: Re: svn commit: r960602 - in /commons/proper/math/trunk/src:
 main/java/org/apache/commons/math/analysis/interpolation/
 main/java/org/apache/commons/math/exception/
 main/java/org/apache/commons/math/util/
 main/resources/META-INF/localization/ site/xdoc/ tes...
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> >> The stack trace certainly will show where the bad thing happened.
> >> Nothing important is lost: What went wrong is as clearly identified by
> >> saying
> >>  "The argument must be >= 2"
> >> as by saying
> >>  "The number of points must be >= 2"
> >> The problem is that the caller passed a wrong argument and this is a bug and
> >> no amount of detailed message will be a substitute for reading the
> >> documentation and source code and make the correct call.
> > 
> > Sorry, but I disagree here.  There is definitely loss of information
> > in the stack trace. I would prefer to retain the detailed error
> 
> I also disagree with Gilles, but not the same reason. Some people will
> not have access to the stack trace. It is even more important for
> unchecked exception since they may not be intercepted by high level
> applications. All they will get is a terse message print on a log file
> or a popup window before the application stops.
> 
> Users are not here to debug the code for developers.
> 
> Also the Apache license allows people to reuse our code in proprietary
> environment with closed source. For sure in this case, no stack trace
> will be available.
> 
> Luc

And I disagree with both your disagreements. Could you _please_ answer all
the drawbacks of your approach in several scenarios which I've put forward
many times already, instead of always only cling to the one use-case which
you are interested in?

Please! What kind of ?@#! application is it that you take as an example,
that will print a terse message and exit?  The _least_ a program should
do when it bails out is print the stack trace!

Please! Read chapter 8 of Bloch's Effective Java (less then 20 pages) to see
that indeed the error message must be reported by the user/operator to the
developer. This is not debugging.

> > message that tells what quantity was "too small."  And I do not
> > really see the value in the "NumberTooSmallException" altogether,
> > frankly.  By substituting an exception that does not identify what
> > quantity was "too small" for an IllegalArgumeentException with a
> > message giving the full context, what exactly have we achieved?

Then perhaps you missed some of the comments here above, and also at
  https://issues.apache.org/jira/browse/MATH-195
and/or at
  https://issues.apache.org/jira/browse/MATH-361
and references therein (Bloch, Goetz).

Or perhaps we (Eckel et al.) are all wrong. In this case, please show me
modern, high-profile, Java library projects that deal with exceptions in
the same way that you want it for CM.


Gilles

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