Compose Attributes

compose_attrs.rb

  def compose_attrs(a, b)
    result = a.dup
    b.each do |key, val|
      x = result[key]
      y = val
      pair = [ x, y ]
      if pair.any?(&:nil?)
        result[key] = x || y
      elsif pair.all? Hash
        result[key] = compose_attrs(x, y)
      elsif pair.all? String
        result[key] = [ x, y ].join(" ")
      else
        result[key] = val
      end
    end
    result
  end