From: "ara.t.howard" <ara.t.howard@...>
Date: 2007-11-09T12:43:19+09:00
Subject: Re: Best practises for exception handling


On Nov 8, 2007, at 7:20 PM, Joel VanderWerf wrote:

> Another possibility, somewhere between a and b: rescue the  
> exception and re-raise, but add some more information to the  
> message. That extra info might be, for example, IP address and port  
> during network operations. This doesn't change the structure of  
> exception handling, since the Exception subclass is the same and it  
> will be handled at the same point, eventually, but it can be very  
> useful for logging/debugging and for presenting an informative  
> message to the user, if your program is interactive.

good point joel, i recently added this to main:

...

                 rescue Exception => e
                   handle_exception e
                 end
...

     def handle_exception e
       if e.respond_to?(:error_handler_before)
         fcall(e, :error_handler_before, self)
       end

       if e.respond_to?(:error_handler_instead)
         fcall(e, :error_handler_instead, self)
       else
         if e.respond_to? :status
           exit_status(( e.status ))
         end

         if Softspoken === e or SystemExit === e
           stderr.puts e.message unless(SystemExit === e and  
e.message.to_s == 'exit') ### avoids double message for abort('message')
         else
           fatal{ e }
         end
       end

       if e.respond_to?(:error_handler_after)
         fcall(e, :error_handler_after, self)
       end

       exit_status(( exit_failure )) if exit_status == exit_success
       exit_status(( Integer(exit_status) rescue(exit_status ? 0 : 1) ))
       exit exit_status
     end

...

which basically allows exceptions to be extended with modules or have  
methods defined on them which affect how they are handled.  it seems  
like a useful pattern but i've only just started using it.

cheers.

a @ http://codeforpeople.com/
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