Use of current_user setter in Ruby on Rails Tutorial by Michael Hartl?

Question

I'm a little confused here. In chapter 8 of the fabulous Ruby on Rails Tutorial by Michael Hartl, I can't figure out why Michael uses a setter to set the instance variable @current_user to user.

module SessionsHelper

  def sign_in(user)
    remember_token = User.new_remember_token
    cookies.permanent[:remember_token] = remember_token
    user.update_attribute(:remember_token, User.encrypt(remember_token))
    self.current_user = user
  end

  def current_user=(user)
    @current_user = user
  end
end

Why did he not just skip the setter method and do it this way instead?

module SessionsHelper

  def sign_in(user)
    remember_token = User.new_remember_token
    cookies.permanent[:remember_token] = remember_token
    user.update_attribute(:remember_token, User.encrypt(remember_token))
    @current_user = user
  end
end

Is it just because it's best practice to implement a setter or I don't get something?

Answer 1

This is just an OO question. Because the current_user= is part of the session's contract with the world. It is promising that, no matter where the user is ultimately stored (such as in User.current_user), you can always set it thru that interface.

Answer 2

I haven't read it, but he could be

• Making a point
• Following best practice
• Intending to use the setter elsewhere, earlier or later in the tutorial

Answer 3

I am pretty sure he reuses that method later when the user loads another page. Something like:

# in application_controller
before_filter :authenticate

private
def authenticate
  if cookies[:remember_token]
    self.current_user = User.authenticate(cookies[:remember_token])
  end
end

# in user.rb
def self.authenticate(token)
  find_by_remember_token(User.encrypt(token))
end