From: Trans <transfire@...>
Date: 2006-10-02T21:10:08+09:00
Subject: Re: Why can't I get on Top?


Jeffrey Schwab wrote:

> module Test
>      def self.included( base )
>          p base == $toplevel
>      end
> end
>
> class << self
>
>      # $toplevel has to be set in here,
>      # where it can really refer to the
>      # including object.
>
>      $toplevel = self
>      include Test
> end

In your example you are controlling the inclusion from the start.
That's missing the point. The #included callback catches the inclusion
of a module and _reacts_ to that. The module is a resuable lib that an
end-user/programmer may well include at the toplevel and the module
should just work. Otherwise one has to document: "IMPORTANT: don't
include at toplevel, It won't work...."

But you also may not realize that methods defined at the toplevel do
not go to the singleton. They go to Object itself. So really your
example should be:

  class Object
      $toplevel = self
      include Test
  end

But you are getting a false positive, since:

  module NotTheTopLevel
      $toplevel = self
      include Test
  end    

works too.

T.