From: Brian Hartin <brian.hartin@...>
Date: 2008-04-03T03:45:01+09:00
Subject: Re: Does Ruby support exception wrapping (exception chaining

Joel,

This doesn't really provide the main benefit to exception wrapping 
mechanism:  the ability to wrap low-level exceptions in an appropriate 
higher-level exception and yet not lose the entire stack trace, or the 
types and messages of the low-level exceptions.  Exception wrapping 
(a.k.a. chaining) in Java (a good model for this feature, I think) makes 
the idea of a 'causal Exception' part of the class (via a 'cause' 
field), and the stack trace: an Exception's stack trace includes the 
causal 'chain' of Exceptions automatically.

I think I can write this up for my own use.  I just wondered if I was 
missing an existing feature.

Thanks for the response!


Joel VanderWerf wrote:
> Hartin, Brian wrote:
>> end
> The second arg to raise (i.e. the message) can be any object:
> 
> class ServiceNotFoundException < StandardError; end
> 
> begin
>    begin
>      raise "foo"
>    rescue Exception => e
>      raise ServiceNotFoundException, ["The service could not be 
> contacted",
>    e]
>    end
> rescue Exception => e_outer
>    puts e_outer
>    p e_outer.message
> end
> 
> __END__
> 
> Output:
> 
> #<ServiceNotFoundException:0xb7d9b75c>
> ["The service could not be contacted", #<RuntimeError: foo>]

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