gistfile1.builder

  def test_deep_merge
    @ordered_hash['deep'] = ActiveSupport::OrderedHash.new
    @ordered_hash['deep']['number'] = 1
    @ordered_hash['deep']['place'] = 'here'

   other_hash = ActiveSupport::OrderedHash.new
   other_hash['deep'] = ActiveSupport::OrderedHash.new
   other_hash['deep']['number'] = 5

   merged = @ordered_hash.deep_merge(other_hash)

   #should merge the nested hash
   assert_equal 5, merged['deep']['number']
   assert_equal 'here', merged['deep']['place']
  end


  def test_deep_block_merge
    @ordered_hash['deep'] = ActiveSupport::OrderedHash.new
    @ordered_hash['deep']['number'] = 1
    
    other_hash = ActiveSupport::OrderedHash.new
    other_hash['deep'] = ActiveSupport::OrderedHash.new
    other_hash['deep']['number'] = 5
    other_hash['deep']['place'] = 'here'
    
    merged = @ordered_hash.deep_merge(other_hash){|key, old_value, new_value| old_value + new_value}
    
    #should merge the nested hash
    assert_equal 6, merged['deep']['number']
    assert_equal 'here', merged['deep']['place']
  end

gistfile2.builder

class Hash
  # Returns a new hash with +self+ and +other_hash+ merged recursively.
  def deep_merge(other_hash, &block)
    dup.deep_merge!(other_hash, &block)
  end

  # Returns a new hash with +self+ and +other_hash+ merged recursively.
  # Modifies the receiver in place.
  def deep_merge!(other_hash, &block)
    other_hash.each_pair do |k,v|
      tv = self[k]
      if tv.is_a?(Hash) && v.is_a?(Hash)
        self[k] = tv.deep_merge(v, &block)
      else
        if block_given? and (!tv.nil? and !v.nil?) 
          self[k] = yield(k, tv, v)
        else
          self[k] = v 
        end
      end
    end
    self
  end
end