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From: 7stud -- <bbxx789_05ss@yahoo.com>
Newsgroups: comp.lang.ruby
Subject: Re: Making a simple parser
Date: Mon, 18 Apr 2011 13:24:32 -0500
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Xref: x330-a1.tempe.blueboxinc.net comp.lang.ruby:3113

I'm pretty unclear about what you are trying to do, but maybe this will 
help:

class InputFormat
  @children = []

  def self.children
    @children
  end

  def initialize(input)
    @input = input
  end

  def parse
    InputFormat.children.each { |child|
      child.parse(@input) if child.supported?
    }
  end

  def self.inherited(sub_class)
    @children << sub_class.new('dummy')
  end
end



class InputFormatA < InputFormat
  def supported?
    true
  end

  def parse(str)
    puts "InputFormatA is parsing #{str}"
  end
end

class InputFormatB < InputFormat
  def supported?
    true
  end

  def parse(str)
    puts "InputFormatB is parsing #{str}"
  end
end



input = InputFormat.new('hello world')
input.parse

--output:--
InputFormatA is parsing hello world
InputFormatB is parsing hello world


Note that when inherited() is called, the methods of the subclass are 
not defined yet, so the inherited initialize() is called.

-- 
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