takes_long_time.rb

require 'rubygems'
require 'eventmachine'

class Handler
  include EventMachine::Deferrable
  
  def takes_long_time(seconds = 5)
    sleep(seconds)
    puts "Awoke after #{seconds} seconds."
    succeed(seconds)
  end
  
  def self.takes_long_time(seconds)
    obj = new
    obj.takes_long_time(seconds)
    obj.callback do |result|
      puts "Sleeping #{result} seconds succeeded."
    end
    obj
  end
  
end

EM.run do
  
  results = []
  
  a = Handler.takes_long_time(1)
  b = Handler.takes_long_time(2)
  
  [a, b].each do |obj|
    obj.callback do |result|
      results << result
      if results.size == 2
        puts "We're done"
      end
    end
  end
  
end