From: Anurag Priyam <anurag08priyam@...>
Date: 2011-05-29T00:30:50+09:00
Subject: Re: Unexpected behavior when referencing nested classes

> Have I misunderstood how constants work?

Yeah. Ruby first tries to find the constant in the "lexical scope" of
the reference - immediately enclosing module/class, then the next
enclosing module/class, and so on.

You can find out the modules/classes that are searched by calling
Module.nesting method at that point.

> class Foo::Bar::Baz; def say; "::Foo::Bar::Baz";
> end; def x; Baz.new.say; end; end
> Foo::Bar::Baz.new.x

Here, Baz is first looked up in Foo::Bar::Baz, and then the global
namespace; confirm with Module.nesting. Ruby finds Baz in the later,
so '::Baz is the expected output.

module Foo::Bar
  class Baz
    def say; "::Foo::Bar::Baz"; end
    def x; Baz.new.say; end
  end
end

Foo::Bar::Baz.new.x #=> "::Foo::Bar::Baz"

Here, Ruby first looks up Baz in Foo::Bar::Baz, followed by Foo::Bar
finds, and then the global namespace. Again, you can confirm this with
Module.nesting.

Sometime back, I had answered a similar question. You might want to
have a look[1].

[1]: http://groups.google.com/group/ruby-talk-google/browse_thread/thread/5f3066bf9366e44f#

-- 
Anurag Priyam
http://about.me/yeban/