From: Dave Cantrell <ruby-talk@...>
Date: 2006-02-24T12:39:12+09:00
Subject: Re: What's mean? global variables

Jacob Fugal wrote:
> $test is a global variable. Thats important in this case for scope --
> $test continues to exist and retain its value between invocations of
> test. The ||= idiom is one commonly found in ruby. It's similar to +=
> in that it is simply short hand for "$test = $test || Test.new". $test
> starts with a value of nil, and the first time test is run (unless you
> manually set $test beforehand), $test is initialized to a new instance
> of Test, since "(nil || anything) == anything". On subsequent runs,
> $test retains its value. From this behavior, ||= can be thought of as
> a "default initializer" operator.

Jacob,

So is this a shortcut for creating a singleton in Ruby? Albeit a 
slightly different one I would guess, using a global variable to store a 
single instance rather than using a class method to instantiate a new or 
return the existing instance.

Thanks...
-dave