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NNTP-Posting-Date: Fri, 10 Jun 2011 03:30:07 -0500
Date: Fri, 10 Jun 2011 01:30:03 -0700
From: Patricia Shanahan <pats@acm.org>
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Subject: Re: Call by Result
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On 6/9/2011 11:03 PM, Gene Wirchenko wrote:
> Dear Java'ers:
>
>       I wish to call by result with a method.  Is it possible?  If not,
> can it be easily simulated in an unnasty way?
>
>       I am writing a simple preprocessor.  I have a few spots where a
> string needs to be parsed.  I want to call something like this:
>            String ReturnString="";
>            boolean DidItWork=GetString(ReturnString);
>            if (!DidItWork)
>               // too bad
> It is not acceptable to have a special String value mean failure.  I
> want the method to be able to return any potential string.

Exceptions provide an alternative. Rather than returning a didItWork
boolean, return the String if it did work, and throw an exception if it
did not work.

In addition to allowing the method to return its primary result, it also
allows for passing back more information in the case of failure, which
can lead to better reporting.

Patricia