⚠️ I would only use something like CurrentAttributes sparingly if at all. If something like global state makes sense for a certain use cases, consider a safer alternative https://github.com/dry-rb/dry-effects (they say it isn’t global state, but it is just with more explicit code and errors that get raised to enforce using it ’safely’).

Reader for example, allows passing a value down the stack. It’s strictly for reading, so if writing state down the stack is needed, use the State effect.

class ApplicationController < ActionController::Base
  include Dry::Effects::Handler.Reader(:current_user)

  around_action :provide_current_user

  def provide_current_user(&block)
    user = User.find_by(id: cookies.encrypted[:user_id])
    with_current_user(user, &block)
  end
end

class ThingThatDoesStuff
  include Dry::Effects.Reader(:current_user, default: nil)

  def call
    current_user.things
  end
end

Why is the better than CurrentAttributes?

• Must explicitly declare (via module inclusion) which classes can read or set the global state
• Accessing global state before it is set raises an error