EM-Promise

A promise / deferred implementation for EventMachine inspired by AngularJS / Kris Kowal’s Q.

From the perspective of dealing with error handling, deferred and promise apis are to asynchronous programing what try, catch and throw keywords are to synchronous programming.

require 'rubygems'
require 'em-promise'

def asyncGreet(name)
	deferred = EM::Q.defer
	
	EM::Timer.new(5) do
		EM.defer do
			deferred.resolve("Hello #{name}")
		end
	end
	
	deferred.promise
end


EventMachine.run do

	asyncGreet('Robin Hood').then(proc { |greeting|
		p "Success: #{greeting}"
	}, proc { |reason|
		p "Failed: #{reason}"
	})
	
	asyncGreet('The Dude').then do |greeting|
		p "Jeff '#{greeting}' Lebowski"
	end
	
end

Start using it now

1. Read the Documentation
2. Then gem install em-promise