とりあえず準備体操。 require 'enumerator' class Fib def fib a = 1 b = 1 loop do yield(a) tmp = a; a = b; b = tmp + b; end end end fib = Fib.new.enum_for(:fib) g = fib.each 10.times do p g.next end ~/work$ ruby foo.rb 1 1 2 3 5 8 13 21 34 5…