Ruby's Enumerator in Ruby

simple_enumerator.rb

class SimpleEnumerator
  def initialize(&block)
    raise ArgumentError unless block_given?
    @block = block
  end

  def take(num)
    @fiber = Fiber.new do
      @block.call(EnumYielder.new)
    end

    ary = []
    num.times do
      ary << self.next
    end

    ary
  end

  private

  def next
    @fiber.resume
  end
end

class EnumYielder
  def <<(value)
    Fiber.yield(value)
  end
end