An example of argument handling change for em-synchrony

sync-args-example.rb

#!/usr/bin/env ruby

require 'rubygems'
require 'eventmachine'
require 'em-synchrony'

module EventMachine
  module Synchrony
    def self.new_sync(df)
      f = Fiber.current
      xback = proc {|*args|
        if f == Fiber.current
          return *args
        else
          f.resume(*args)
        end
      }
      df.callback &xback
      df.errback &xback

      Fiber.yield
    end
  end
end

def gimme_deferreds
  a, b = EM::DefaultDeferrable.new, EM::DefaultDeferrable.new

  EM.next_tick do
    a.succeed(1, 2, [:foo, :bar])
    b.succeed(:single_arg)
  end

  return a, b
end


def current_implementation
  EM.synchrony do
    a, b = gimme_deferreds

    rval = EM::Synchrony.sync(a)
    puts "a rval: #{rval.inspect}"

    rval = EM::Synchrony.sync(b)
    puts "b rval: #{rval.inspect}"

    EM.next_tick { EM.stop_event_loop }
  end
end

def proposed_fix
  EM.synchrony do
    a, b = gimme_deferreds

    rval = EM::Synchrony.new_sync(a)
    puts "a rval: #{rval.inspect}"

    rval = EM::Synchrony.new_sync(b)
    puts "b rval: #{rval.inspect}"

    EM.next_tick { EM.stop_event_loop }
  end
end


if __FILE__ == $0
  puts <<-EOS
call signature: 
a.succeed(1, 2, [:foo, :bar])
b.succeed(:single_arg)

  EOS

  puts "this is the return value of the current implementation:"
  current_implementation

  puts "\nthis is the proposed change:"
  proposed_fix
end

__END__

call signature:
a.succeed(1, 2, [:foo, :bar])
b.succeed(:single_arg)

this is the return value of the current implementation:
a rval: 1
b rval: :single_arg

this is the proposed change:
a rval: [1, 2, [:foo, :bar]]
b rval: :single_arg