From: david karapetyan <dkarapetyan@...>
Date: 2007-08-19T05:52:24+09:00
Subject: Re: method access to the enclosing method's locals?

------=_Part_113679_11164795.1187470348278
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: 7bit
Content-Disposition: inline

Maybe you can answer another question. While trying to figure this out I
kept running into scoping issues. The first thing that popped into my head
was

def go2(arg)
  clos = proc {puts "Hi #{arg}"}
  class << self
    define_method(:hi,clos)
  end
end

but this didn't work because for some reason when I'm inside the scope of
class << self ... end define_method can't find clos even though it is inside
the enclosing scope. Is there a reason classes don't close over their
enclosing scope because I was thinking just like we can have closures we
could also have closures for classes.

On 8/18/07, David A. Black <dblack@rubypal.com> wrote:
>
> Hi --
>
> This isn't quite the same as doing an inner def, because you're
> defining #hi as a singleton method. If you want to define it as an
> instance method of the enclosing class, you would want to do:
>
>    self.class.class_eval do ...
>
> As for the head spinning, hopefully someday we'll have this method in
> the core (and meanwhile you can write it yourself):
>
>    class Object
>      def singleton_class
>        class << self; self; end
>      end
>    end
>
> Then you can do:
>
>    singleton_class.class_eval do ...
>
> which is a little less cluttered. Also, keep in mind that it's not
> really redirection; it's just sending messages to objects :-) The fact
> that you can send messages to Class objects means that you can do what
> feels like "meta" stuff in much the same way that you do other things.
>
>
> David
>
> --
> * Books:
>    RAILS ROUTING (new! http://www.awprofessional.com/title/0321509242)
>    RUBY FOR RAILS (http://www.manning.com/black)
> * Ruby/Rails training
>      & consulting:  Ruby Power and Light, LLC (http://www.rubypal.com)
>
>

------=_Part_113679_11164795.1187470348278--