Message-Based Callbacks

gistfile1.rb

module FmsEngine
  module Core
    class Callbacks
      class << self
        # Redis or something:
        CALLBACK_REGISTRY = Hash.new { |h, k| h[k] = [] }

        def bind(event, klass, callback_method, facade_method)
          CALLBACK_REGISTRY[event] << { klass: klass, callback_method: callback_method, facade_method: facade_method }
        end

        def fire(event, object)
          relevant_callbacks = CALLBACK_REGISTRY[event]

          relevant_callbacks.each do |callback|
            callback[:klass].send(callback[:callback_method], object.send(callback[:facade_method]))
          end
        end
      end
    end
  end
end

module FmsEngine
  module Billing
    class SomeClass
      FmsEngine::Core::Callbacks.bind('enrollment.consumer.created', self, :new_consumer, :demographic_info)
      # FmsEngine::Core::Callbacks.bind('consumer.update', self, :update_my_consumer)

      def self.new_consumer(demographic_info)
        p demographic_info
      end

      def self.update_my_consumer(consumer_id)
        p "Consumer #{consumer_id.to_s} was Updated"
      end
    end
  end
end

module FmsEngine
  module Enrollment
    class Consumer
      def physical_address
        'Some Address'
      end

      def first_name
        'Jim'
      end

      def last_name
        'Halpert'
      end
    end

    class ConsumerFacade
      def initialize(consumer)
        @consumer = consumer
      end

      def address
        @consumer.physical_address
      end

      def demographic_info
        { first_name: @consumer.first_name, last_name: @consumer.last_name }
      end
    end

    class ConsumerPublisher
      def self.updated_consumer(id)
        FmsEngine::Core::CallbackRegistry.fire_callback('consumer.did_update', id)
      end

      def self.created_consumer(id)
        consumer_facade = ConsumerFacade.new(Consumer.new)
        FmsEngine::Core::Callbacks.fire('enrollment.consumer.created', consumer_facade)
      end
    end
  end
end

FmsEngine::Enrollment::ConsumerPublisher.created_consumer(12)