From: Joel VanderWerf <vjoel@...>
Date: 2005-01-20T03:39:51+09:00
Subject: Re: is defined? fast?

Florian Gross wrote:
> Robert Klemme wrote:
> 
>> Personally I never felt the need for defined? - only during my
>> initial Ruby stages, when I carried some Perl thinking with me; but
>> never after I got rid of that. :-)
> 
> 
> I always thought it was there mostly for using it in IRB, not in actual
> code. (E.g. to ask Ruby how it understands a construct.)
> 
> But it does at least make sense in real code in the defined?(Constant) 
> case.

The following idiom is useful in mixins:

   module Mixin
     def meth
       super if defined?(super)
       # add some behavior here
     end
   end