An introduction to eventmachine, and how to avoid callback spaghetti

An introduction to #eventmachine, and how to avoid callback spaghetti #ruby

require 'rubygems' require 'em-http' require 'json' class LanguageDetector URL = "http://www.google.com/uds/GlangDetect" include EM::Deferrable def initialize(text) request = EM::HttpRequest.new(URL).get({ :query => {:v => "1.0", :q => text} }) # This is called if the request completes successfully (whatever the code) request.callback { if request.response_header.status == 200 info = JSON.parse(request.response)["responseData"] if info['isReliable'] self.succeed(info['language']) else self.fail("Language could not be reliably determined") end else self.fail("Call to fetch language failed") end } # This is called if the request totally failed request.errback { self.fail("Error making API call") } end end EM.run { detector = LanguageDetector.new("Sgwn i os yw google yn deall Cymraeg?") detector.callback { |lang| puts "The language was #{lang}" } detector.errback { |error| pu...

Full article: http://rubylearning.com/blog/2010/10/01/an-introduction-t...