From: Robert Klemme <bob.news@...>
Date: 2004-10-22T23:09:16+09:00
Subject: Re: #extend_object only for #extend and not #include


"Gavin Kistner" <gavin@refinery.com> schrieb im Newsbeitrag
news:8529C86C-2430-11D9-A186-000A959CF5AC@refinery.com...
> Just thought I'd point out my surprise that the Module#extend_object
> callback only fires when #extend is explicitly called, and not when the
> module extends the class via #include:
>
> module Foo
> def self.extend_object( o )
> p "#{o} just extended by #{self}"
> end
> end
>
> class Bar; include Foo; end
> class Bar2; self.extend( Foo ); end
>
> #=> "Bar2 just extended by Foo"

Well, that's quite logical, isn't it?  I mean, include and extend are two
different cups of tea.

Apart from the solution Guy posted you can do this:

module Foo
  def self.extend_object( o )
    p "#{o} just extended by #{self}"
  end

  def self.included( o )
    p "#{o} just included #{self}"
  end
end

>> class Bar; include Foo; end
"Bar just included Foo"
=> Bar
>> class Bar2; self.extend( Foo ); end
"Bar2 just extended by Foo"
=> Bar2


And for classes there is #inherited:

class Base
  def self.inherited(cl)
    p "#{cl} just inherited #{self}"
  end
end


>> class Derived < Base ; end
"Derived just inherited Base"
=> nil


Kind regards

    robert