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From Ugo Cei <u....@cbim.it>
Subject Re: [RT] Checked exceptions considered harmful
Date Wed, 14 Apr 2004 14:05:06 GMT
Carsten Ziegeler wrote:
> In general I agree with Bertrand that it's nicer to add
> a "throws Exception" to an Interface to tell the user
> that something can go wrong.

You will get to add a "throws Exception" to any method only over my dead 
body ;-).

> And we shouldn't forget that some exceptions are treated
> differently, for example the ResourceNotFound exception
> (that's the reason for the ugly exception handling code
> in SourceUtil). This exception is treated by the
> sitemap engine differently from other exceptions and
> we shouldn't loose this feature.

Indeed. That's why I propose that ProcessingException extends 
CascadingRuntimeException, instead of CascadingException. This way, you 
won't be forced to catch it (and catch ResourceNotFoundException) if you 
don't need to and be tempted to wrap it or swallow it.

The sitemap engine can continue catching it as it does now.

The litmus test should be the following: can you recover from a 
ResourceNotFoundException, in the general case? IMHO, no. Your best 
course of action is to tell the user.

If I'm not mistaken, reparenting ProcessingException would require zero 
changes in other components, it would be a totally backward-compatible 
change, but could allow us to remove lots of useless code. So I'm 
proposing to do this for 2.1.5.

Removing or changing the "throws" clause of public interfaces would be 
an incompatible change, so we can discuss it for 2.2 or later.

	Ugo


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