From: Trans <transfire@...>
Date: 2005-04-13T09:04:36+09:00
Subject: Re: help traversing and modifying hash key and value inplace

So here's what I've settled on. Good? Or is there still a better way to
do?

 # Returns a new hash created by traversing the hash and its subhashes,
  # executing the given block on the key and value. The block should
  # return a 2-element array of the form +[key, value]+.
  #
  #   h = { "A"=>"A", "B"=>"B" }
  #   h.traverse { |k,v| [k.downcase, v] }
  #   h  #=> { "a"=>"A", "b"=>"B" }
  #
  def traverse(&b)
    inject({}) do |h,(k,v)|
      nk, nv = b[k,v]
      h[nk] = (Hash === nv ? nv.traverse(&b) : nv)
      h
    end
  end