From: "Shirai,Kaoru" <shirai@...1jp.com>
Date: 2002-07-07T10:09:20+09:00
Subject: Re: passing to objects at the bottom

 Hi.

> i have a chain of objects such that one object contains another which
> contains another, and so on, down the line. the top object recieves a
> parameter which only the bottom most object in the chain is going to
> need. but how do i get it down there with out passing it through all
> the rest? and not using a global variable?

 How about using Environmental Acquisition? (Came from Python.)  In
Ruby, it is required that the package 'OBAQ' is installed. You can get
here:

http://devel.p1jp.com/snapshot/obaq-LATEST.tar.gz

 Let's do same thing to Top/Middle/Bottom example.

  require 'obaq/option'
  
  class Top
    include Obaq::Acquisition
    def a
      "Thanks! I need that."
    end
    acq_export_attr :a
  end
  
  class Middle
    include Obaq::Acquisition
  end
  
  class Bottom
    include Obaq::Acquisition
    acq_import :a
    def put_a
      puts a
    end
  end
  
  top = Top.new
  middle = Middle.new
  middle.set_outer(top)
  bottom = Bottom.new
  bottom.set_outer(middle)
  
  bottom.put_a

 This is very convinient in the situation that it is needed to call the
method of far upper objects on object chain.

-- 
shirai@p1jp.com

Shirai,Kaoru
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