Question

I don’t understand when and what calls this function:

def current_user
 @current_user ||= user_from_remember_token
end

it’s from: http://ruby.railstutorial.org/chapters/sign-in-sign-out#code:current_user_working

When it kick in?

Answer 1

A little higher up you’ll see this:

class ApplicationController < ActionController::Base
  protect_from_forgery
  include SessionsHelper
end

This means that current_user is available in all your controllers and all your views. So any time you need to know who the current user is for access control, filtering data, assigning a creator to a new object, put their name in the upper right corner of the page, etc. you can ask current_user.