From: Pete McBreen <pete@...>
Date: 2002-04-13T12:12:32+09:00
Subject: Re: Rudy idiom for enumeranting parents of a node?

Brad Cox wrote

>I need to enumerate the parentage chain of the nodes in a
>doubly-linked tree. No problem in C/Java, but I'm still too new to
>Ruby to see how. Can someone help?


I though that this one would be easy to answer until I realized that
although there is a #block_given? method I don't know how to refer to an
anonymous given block. A very crude hack is to say

class Node
  def initialize(parent, children=[])
   @parent = parent
   @children = children
   @children.each { |child| child.parent(self) }
 end
 def parents (*unused_args, &block)
   @parent.parents &block unless @parent.nil?
   yield self
  end
end

p = Node.new(nil)
p2 = Node.new(p)

p2.parents {|o| p o}

If this isn't what you want please let me know

Pete
----
Pete McBreen, McBreen.Consulting , Cochrane, AB
email: petemcbreen@acm.org    http://www.mcbreen.ab.ca/

Author, "Software Craftsmanship The New Imperative"
Addison-Wesley (C) 2002
http://www.amazon.com/exec/obidos/ASIN/0201733862
Finalist for the 2002 Jolt Awards