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    <p>Exceptions should really be used when you can't handle the input anymore. They are the special case where your code says "I give up, I'm missing some information or I wasn't meant for this". This is a grey area on how to define such cases, but the usual philosophy, as put by Bill Venners in <a href="http://www.artima.com/designtechniques/desexcept.html">this (old!) article</a> is:</p> <blockquote> <p>Avoid using exceptions to indicate conditions that can reasonably be expected as part of the typical functioning of the method.</p> </blockquote> <p>In your case, it sounds like the content you have to parse might be incorrect, but this is expected by your program and doesn't break enough the contract to stop the parsing. On the other hand, an acceptable exception would be valid to use if an error in the syntax of the input causes the rest of the interpretation to fail, for example. </p> <p>But people still uses exception because they are quite convenient for stopping execution and going up the stack without going in the tedious details of flowing through returns of results. But on its counterpart, they can have tricky results as you leave some unattended state in some objects. </p> <p>Your requirements sounds more like a validation pattern is required than one single exception that could cause the processing to stop. One exception to stop all processing: if you throw one, the rest will be ignored. But you suggested that you would collect them instead of throwing those. So I'd say, in that case, why use exceptions at all? It seems you do want to return proper results and not stop the program's execution.</p> <p>Because if you still go down this path, you could have a collection of exceptions to throw at the end. Which one do you throw? Which one takes precedence, in the Exception collector you created?</p> <p>Take the example of Eclipse, which has this gigantic platform to handle with a massive collection plug-ins contribution. They use a proper communication channel to log any warning and errors, either in problems pane or <a href="http://www.vogella.com/articles/EclipseJobs/article.html#eclipsejobs_progress">through the execution of background task</a>. The latter's execution will usually return an <a href="http://help.eclipse.org/indigo/index.jsp?topic=/org.eclipse.platform.doc.isv/reference/api/org/eclipse/core/runtime/IStatus.html">IStatus object</a> or a variant. Based on this <code>IStatus</code> object, the code that receives the status decides to act upon it.</p> <p>Hence personally, I'd develop a similar object that would collect all necessary user's errors (and not program's errors), that does not break the program's execution and an acceptable part of the contract. This object can contain the severity of the error, its source, a hint on how to fix it (this can be a string, or even a method that contains a pinpointing logic for showing the error or possibly a partial automated fix), etc... Once the execution is done, the parsing's result will get these status objects and act on it. If there are errors, inform the user through the UI and log it as well.</p> <p>So it's basically the same approach as you initially suggested, minus the exceptions and minus the commodity of jumping through the stack that could lead to nasty side-effects and very difficult to debug errors.</p>
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