iterator.rb

class ArrayIterator
  def initialize(array)
    @array = array
    @index = 0
  end

  def has_next?
    @index < @array.length
  end

  def item
    @array[@index]
  end

  def next_item
    value = @array[@index]
    @index += 1
  end
end

array = ["red","blue","green"]
i = ArrayIterator.new(array)
while i.has_next?
  puts "item: #{i.next_item}"
end

i = ArrayIterator.new('abcd')
while i.has_next?
  puts "item: #{i.next_item.chr}"
end