promise_runner.rb

require 'promise'

class PromiseRunner
  attr_reader :promise

  def initialize
    @promise = Promise.new
  end

  def test
    @promise = @promise.then do |v|
      puts "Original #{v.inspect}"
      return 10
    end
  end

  def second
    @promise.then do |v|
      puts "GOT: #{v}"
    end
  end
end

pr = PromiseRunner.new
pr.test
pr.second
pr.promise.resolve(20)