From: Rob Biedenharn <Rob@...>
Date: 2009-02-26T03:06:30+09:00
Subject: Re: Using "rescue" inline

On Feb 25, 2009, at 12:11 PM, Iņaki Baz Castillo wrote:

> Hi, is it correct the following "rescue" usage?
>
> myvar = 1  # Fixnum
> othervar = myvar.downcase rescue myvar
> => 1
>
> It seems to work, but is it really correct? Thanks.
>
> --  
> Iņaki Baz Castillo
> <ibc@aliax.net>


Hmm, "correct"? Well, it is certainly legal syntax and is equivalent to:

othervar = begin
              myvar.downcase
            rescue
              myvar
            end

But, it might not be the best way to shave the yak.

othervar = myvar.respond_to?(:downcase) ? myvar.downcase : myvar

might perform better if the exception to be rescued is expensive to  
construct only to then be thrown away.  (I don't know if there's any  
special optimization of the expression form of rescue compared to the  
block form.)

It also can hide problems that you won't know that you have. For  
example,
   myvar = nil
   othervar = myvar.downcase rescue myvar
Did you want to set othervar to nil also?
Perhaps you need othervar as a downcased String? Maybe it would be  
better as:
   othervar = myvar.to_s.downcase

In any case, you'd have to decide.

-Rob


Rob Biedenharn		http://agileconsultingllc.com
Rob@AgileConsultingLLC.com