From: John Carter <john.carter@...>
Date: 2005-11-14T04:40:35+09:00
Subject: Re: Logging vs. Exceptions

On Fri, 11 Nov 2005, lroland@gmail.com wrote:

>      begin
>        session = UNIXSocket.new(@socket)
> 	session.send(msg,0)
> 	data = session.recvfrom(512)[0] # [0] ensures we only get clam's
> respons
> 	session.close()
>      rescue
>        raise ScannerException.new("unable to use socket: #{@socket}")
>      end

Evil! Evil! Evil! DON'T _DO_ THAT!

You have now masked every error in that section and munged them into one. 
You could have a simple programming bug, or something weird may be 
happening on your system, but it will all collapse into one error and you 
will have not the foggiest idea what happened or why.


So try one of these variants...

best practice would be trap just those exceptions you know can arise..

   rescue ASpecificError
     raise ScannerExecption.new(.....)
   end

or (if you must catch all) at least record what it was, don't mask the 
unexpected.

   rescue Exception => details
     raise ScannerException.new( "blah blah #{details}")
   end

or, since you are not really adding much of value at this level, just 
don't catch anything at this level, (never catch an exception you don't 
know how to handle.)



John Carter                             Phone : (64)(3) 358 6639
Tait Electronics                        Fax   : (64)(3) 359 4632
PO Box 1645 Christchurch                Email : john.carter@tait.co.nz
New Zealand

Carter's Clarification of Murphy's Law.

"Things only ever go right so that they may go more spectacularly wrong later."

From this principle, all of life and physics may be deduced.