Smart enumerator with smart enumerable items

_smart_enumerator.rb

class SmartEnumerator < Enumerator
  attr_reader :length

  def initialize(enumerable)
    super
    @length = enumerable.length
  end

  def each
    self.each_with_index do |item, index|
      yield SmartEnumerableItem.new(item, index, self.length)
    end
  end
end

class SmartEnumerableItem
  def initialize(item, index, parent_length)
    @item = item
    @index = index
    @parent_length = parent_length
  end

  def first?
    @index.zero?
  end

  def last?
    @index + 1 == @parent_length
  end

  def to_s
    @item.to_s
  end

  def method_missing(name, *args, &block)
    @item.send name, *args, &block
  end
end

for_example.rb

x = SmartEnumerator.new([1,2,3,4,5])
x.each {|i| i.first? ? puts(i.to_s.inspect) : i.last? ? puts("#{i} is the last one") : puts(i**i)}
"1"
4
27
256
5 is the last one