From: "David A. Black" <dblack@...>
Date: 2003-11-29T08:20:34+09:00
Subject: Re: re-raising an exception with the original backtrace

Hi --

On Sat, 29 Nov 2003, Joel VanderWerf wrote:

> 
> Is there a way to re-raise an exception without replacing its backtrace 
> with the current one?
> 
> The reason I want to do this is that I am catching an exception and 
> passing it to a handler. The handler needs to make a decision and then, 
> possibly, re-raise the same exception, preferrably with the same 
> information as it originally contained.
> 
> But if I do the following, the exception takes on the backtrace of the 
> handler, which has lost some information. I know I can add the original 
> backtrace to the exception's message, but that's not the same thing...
> 
> $ cat exception.rb
> 
>    class MyError < StandardError; end
> 
>    def foo
>      raise MyError
>    end
> 
>    def main
>      foo
>    rescue Exception => e
>      handler(e)
>    end
> 
>    def handler(e)
>      ok = false
>      if ok
>        return true
>      else
>        puts "backtrace:", e.backtrace, "---"
>        raise e

I think if you just do 'raise' there, instead of 'raise e', it will
propagate the original exception and backtrace.


David

-- 
David A. Black
dblack@wobblini.net