From: Intransition <transfire@...>
Date: 2011-07-26T01:23:59+09:00
Subject: Re: Building a tree from the leaves down


On Jul 21, 4:30 pm, Kendall Gifford <zettab...@gmail.com> wrote:

> For fun, here's my OO-oriented approach with inspiration (though different)
> from Robert's solution:
>
> class Hash
>   INDENT = " " * 2
>   def inspect(indent = "")
>     result    = "{\n"
>     processed = 0
>     total     = count()
>     each do |k, v|
>       total  += 1
>       v       = v.is_a?(Hash) ? v.inspect(indent + INDENT) : v.inspect
>       result << indent + INDENT + "#{k.inspect} => #{v}"
>       result << "," if processed < total
>       result << "\n"
>     end
>     "#{result}#{indent}}"
>   end
> end

Always a good idea to make it easier to see what the hell is going
on :-)

> class Tree
>   attr_reader :registry
>   def initialize(parent = :parent)
>     @parent   = parent
>     @registry = {}
>   end
>   def register(node)
>     parent = node.send(@parent)
>     if parent
>       @registry[parent]     ||= {}
>       @registry[parent][node] = @registry[node]
>       register(parent)
>     end
>   end
>   def to_hash
>     @registry.select { |k, v| k.send(@parent_method).nil? }
>   end
> end

Nice, that's pretty easy to understand. Thanks.

FYI, @parent_method, should be @parent.