Wrapping Exceptions

I frequently want to add useful information to the message of an exception. Since the Message property of the Exception class does not have a public setter one option is to wrap the exception raised in another.

//...
catch(Exception e)
{
 throw new Exception("Some useful information.", e);
}

Is this bad practise and if so what is the alternative?开发者_StackOverflow社区

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It's better to create a new exception, with a pointer to the original exception. You can print out both the new information and the message from the old exception.

see this info on InnerException

http://msdn.microsoft.com/en-us/library/system.exception.innerexception.aspx

This is the standard approach, which is why Microsoft has built in support for this into their Exception class.

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There's nothing wrong with doing that, although I would not use the general Exception class if you have more information. Debugging problems is easier the more specific your exception is.

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Looks like the Exception.Data property is what I'm after.

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Original Exception already has that information. You are adding much here unless you create a new Exception e.g. SpecificException which will carry some meaning.

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The one caveat is that you haven't provided any new information for code that might be in a position to handle the exception; you've only provided something useful to the developer while debugging a problem. That might be all you're after, but it seems a bit shortsighted.

I prefer not to throw an exception of exactly the same type, especially one as general as Exception, because I might be able to deal with a ConnectionTimeoutException but have no way to handle a PlanetExplodedException. I wouldn't know how to deal with a generic exception other than, perhaps, to log it.