From: Trans <transfire@...>
Date: 2005-04-09T12:39:38+09:00
Subject: Re: help traversing and modifying hash key and value inplace

Thanks Robert.

I agree about returning self. Since dup can't be used when the object
is immutable  (that's the condition isn't it?) then it would seem
reasonable to return self.

I'm not sure what recursive structures you mean. And I don't see how it
could work if the duping is left to the block. How could a new hash be
built up then?

Hmm... perhaps it would work better if a hash parameter were fed into
the block itself and then that could be used?

  h = h.traverse { |n,k,v| n[k.downcase] = v }

Would that a better approach?

BTW, somone sent me another version similar to my original, but using
inject and somehow getting around the dup problem like so:

  def traverse(&b)
    inject({}) do |h,kv|
      k,v = kv.first.dup, kv.last.dup
      b[k,v]
      h[k] = (Hash === v ? v.traverse(&b) : v)
      h
    end
  end

T.