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From: Elijah Zupancic <elijah@zupancic.name>
Date: Sat, 3 Mar 2012 20:07:39 -0800
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 <CALy1bpfpm6Ft0Jeqsy81g_bCsNGxRrvK0f0sYF0m_x9_1mAHyg@mail.gmail.com>
Subject: [chain] Changing from Exception to RuntimeException
To: Commons Developers List <dev@commons.apache.org>
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As I've been working on the examples and the documentation for v2 of
chain, I've noticed that the API for exception handling of Command and
Chain is clunky.

When executing a command like:

        ProfileContext context = new ProfileContext();
        Command<String, Object, ProfileContext> command = new ProfileCheck();

        try {
            command.execute(context);
        }
        catch (Exception e) {
            throw new RuntimeException(e);
        }

The user of chain has to explicitly catch Exception. If the desire was
to catch the most base error and force the user to deal with it, why
aren't we using Throwable? Anyways, this design leads to less than
elegant code and since we will be breaking the API in v2, I would like
to suggest a different approach.

I suggest that Command and Chain should throw a custom exception class
called ChainException that inherits from RuntimeException. And in the
CommandBase, ChainBase we wrap the catch of Exception in this runtime
exception. Moreover, we would attach to ChainException some optional
debug information about the Context invoked when the exception was
encountered. If anyone thinks that this is a good idea, I can whip up
a patch quickly.

Thanks,
-Elijah

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