h1. EM-Promise

A promise/deferred implementation inspired by "AngularJS":http://docs.angularjs.org/api/ng.$q see this documentation for use cases.

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.

<pre><code class="ruby">
def asyncGreet(name)
	deferred = EM::Defer.new
	
	EM::Timer.new(5) do
		EM.defer do
			deferred.resolve("Hello #{name}")
		end
	end
	
	deferred.promise
end


EventMachine.run do

	promise = asyncGreet('Robin Hood')
	promise.then(proc { |greeting|
		p "Success: #{greeting}"
	}, proc { |reason|
		p "Failed: #{reason}"
	})
	
end

</code></pre>