2つ以上のEnumerableを同時に繰り返す

synciter.rb

# -*- coding: utf-8 -*-

class SynchronizedIterator

  include Enumerable

  def initialize *enumerables
    @enumerables = enumerables.map do |e|
      e.map { |item| item }
    end
  end

  def each &blk
    return self unless blk
    @enumerables.first.length.times do |i|
      blk.call *@enumerables.map { |e| e[i] }
    end
    self
  end

end

module Enumerable

  def sync_each *enumerables, &blk
    SynchronizedIterator.new(self, *enumerables).each &blk
  end

end

["a", "b", "c"].sync_each [1, 2, 3] do |char, num|
  puts "#{char} -> #{num}"
end