From: Robert Klemme <bob.news@...>
Date: 2005-04-22T00:24:31+09:00
Subject: Re: accessor for Class Variable


"Leonardo Francalanci" <lfrancalanci@simtel.it> schrieb im Newsbeitrag
news:4267B7A4.6060708@simtel.it...
> >   class<<self; attr_reader :planingList end
>
>
> Aaargh... what is that? What does it mean?
> Sorry, I'm coming from Java...

Then you'll never know... *evil grin*

Ok, class << x ... end is the singleton class of that instance.  You can
use that to define methods for a certain instance only (in this case it's
the class).  Some examples:

17:20:35 [robert.klemme]: irb
irb(main):001:0> obj = Object.new
=> #<Object:0x101949b8>
irb(main):002:0> def obj.foo() "foo" end
=> nil
irb(main):003:0> obj.foo
=> "foo"
irb(main):004:0> class <<obj
irb(main):005:1>   def bar() "<<" + foo() + ">>" end
irb(main):006:1> end
=> nil
irb(main):007:0> obj.bar
=> "<<foo>>"

As a class is an object much like every other object, you can also define
singleton methods for them:

irb(main):008:0> def String.foo() "foo" end
=> nil
irb(main):009:0> String.foo
=> "foo"
irb(main):010:0> class <<String
irb(main):011:1>   def bar() "<<" + foo() + ">>" end
irb(main):012:1> end
=> nil
irb(main):013:0> String.bar
=> "<<foo>>"
irb(main):014:0>

Does that help?

Kind regards

    robert