base.rb

class EventCanvas::Base
  class << self
    attr_reader :matrix

    def context *context_classes
      @context_classes = context_classes
    end

    def subscribers *subscribers_classes
      @context_classes.each do |kls|
        (@matrix ||= {})[kls] = subscribers_classes
      end
    end

    def [](context)
      (@instances || {})[context] ||= new(context)
    end
  end

  def initialize(context)
    @context_tree = [ *(context.is_a?(Class) ? context : context.class).ancestors ] & self.class.matrix.keys
  end

  def << (publisher)
    @context_tree.each do |class_name|
      self.class.matrix[class_name].each do |listener|
        publisher.subscribe listener.new
      end
    end
  end
end

controller.rb

class ReviewsController < ApplicationController
  def edit
    @form   = submitter.form
    @review = submitter.model
  end

  def update
    Application::EventCanvas[self] << submitter
    @form   = submitter.form
    @review = submitter.model
    submitter.on(:success) { |review| redirect_to success_reviews_path }
    submitter.on(:failure) { |review| render action: :edit }
    submitter.call
  end

  def success
    @page = Page.identified_by('review-success')
  end

  private

  def submitter
    @submitter ||= Reviews::Submitter.new(params)
  end
end

event_canvas.rb

class Application::EventCanvas < EventCanvas::Base

  context     ReviewsController, Rake::Task
  subscribers Reviews::EmailSubscriber

  context     Payment::BaseController, Consultations::Reminder
  subscribers Sms::Subscriber, Email::Subscriber

end