em-hiredis pubsub example

pubsub_example.rb

require 'em-hiredis'

EM.run {
  require 'em-hiredis'
  redis = EM::Hiredis.connect
  
  # If you pass a block to subscribe it will be called whenever a message
  # is received on this channel
  redis.pubsub.subscribe('foo') { |msg|
    p [:received_foo, msg]
  }
  
  # You can also pass any other object which responds to call if you wish
  callback = Proc.new { |msg|
    p [:received, msg]
  }
  redis.pubsub.subscribe('foo', callback)
  
  # Passing such an object is useful if you want to unsubscribe
  redis.pubsub.unsubscribe_proc('foo', callback)
  
  # Or if you want to call a method on a certain object on message
  class Thing
    def receive_message(message)
      puts "Foo received #{message}"
    end
  end
  redis.pubsub.subscribe('foo', Thing.new.method(:receive_message))
  
  # You can also unsubscribe completely from a channel
  # redis.pubsub.unsubscribe('foo')
}