From: dblack@...
Date: 2007-05-18T01:26:45+09:00
Subject: Re: quick question about @ and @@

Hi --

On Fri, 18 May 2007, Mike Steiner wrote:

> What's the difference between @ and @@? Specifically, which should I use if
> I need a global variable in a non-OOP Ruby program?

@var is an instance variable (i.e., it represents the private state of
whatever object is in the role of 'self' at the point where @var
appears).  @@var is a class variable, which is a kind of
de-encapsulated thing shared among a class, its descendants, and all
the instances of all those classes.  There's no connection or relation
between @var and @@var.

$var is a global variable.


David

-- 
Q. What is THE Ruby book for Rails developers?
A. RUBY FOR RAILS by David A. Black (http://www.manning.com/black)
    (See what readers are saying!  http://www.rubypal.com/r4rrevs.pdf)
Q. Where can I get Ruby/Rails on-site training, consulting, coaching?
A. Ruby Power and Light, LLC (http://www.rubypal.com)