action_objects.rb

# app/controllers/feeds_controller.rb
class FeedsController < ApplicationController
  before_action :set_feed

  def show
    # Not sure if I like this but there could be something similar to interactors?
    action do
      _1.success.html { redirect_to @feed, notice: "Success" }
      _1.success.json
      _1.unprocessible { render :new }
    end
  end

  private
    def set_feed
      @feed = … # Instance variables are copied to actions, same as they are for views.
    end
end

module ActionController::ActionObjects
  def self.included(klass)
    klass.mattr_reader :action_objects, default: Hash.new do |objects, action_name|
      objects.store action_name, begin const_get action_name.classify; rescue NameError; nil end
    end

    klass.helper_method :action
  end

  def action
    # Probably needs special handling when we're called from the view side so the constant lookup works.
    action_objects[action_name]&.run(view_assigns)
  end
end

class ActionController::ActionObject
  def self.run(...)
    new(...).tap { _1.process if @_process_added }
  end

  attr_reader :params

  def initialize(params, assigns)
    @params = params
    assign assigns
  end
  include Rails.application.routes.url_helpers

  def self.method_added(method)
    @_process_added = true if method == :process
  end

  private
    def assign(assigns)
      assigns.each { instance_variable_set :"@#{_1}", _2 }
    end
end

# Zeitwerk will automatically load this:
# app/controllers/feeds_controller/show.rb
class FeedsController::Show < ActionController::ActionObject
  # An optional method to implement, which is called when the action is initalized.
  def process # Or respond?
    synchronize
  end

  def entries
    @entries ||= @feed.entries.order(published_at: published_at_order).per_page(params[:per_page])
  end

  # Can't remember what this was for, lol?
  def actions
    …
  end

  private
    def synchronize
      unless @feed.last_checked_at?
        SyncFeedJob.perform_now(@feed, source: :feeds_show)
        @feed.reload
      end
    end

    def published_at_order
      @feed.itunes_type == "serial" ? :asc : :desc
    end
end