Success/failure callbacks in Ruby

callbacks.rb

require 'json'

class PostsController
  def create
    CreatePost.new(params)
      .on_success(&-> {
        render json: {}, status: 200
      })
      .on_failure(&-> {
        render json: {errors: {name: ["can't be blank"]}}, status: 422
      })
      .on_explosion(&-> {
        render json: {booms: "happen"}, status: 500
      })
      .execute
  end

  private

  def render(options={})
    <<-HTTP.gsub(/^\s+/, '')
    HTTP/1.1 #{options[:status]}
    Content-Type: application/json
    #{options[:json].to_json}
    HTTP
  end

  def params
    {author_id: 1, content: 'My first blog post!'}
  end
end

class BaseExecutor
  def initialize
    @callbacks = {}
  end

  def execute
    raise NotImplementedError
  end

  def method_missing(name, *args, &block)
    method_name = name.to_s
    if method_name.start_with?('on_') && block_given?
      @callbacks[method_name.sub(/on_/, '')] = block
      self
    else
      super
    end
  end
end

class CreatePost < BaseExecutor
  def initialize(params)
    super()
    @params = params
  end

  def execute
    @callbacks.values.sample.call
  end
end

puts PostsController.new.create