Question

I’m trying to learn both Ruby and Rails and I’m looking at Michael Hartl’s RailsTutorial.org. In Chapter 7 or 8, he’s working on sessions and I think he’s using a method call as an argument to a function, but I’m not totally sure of it. It’s not something I’ve seen before.

Please have a look at the first function in the “private” section below where the argument is remember_token. does this mean that the return value of the function remember_token becomes the argument(s) for User.authenticate_with_salt?

def current_user
    @current_user ||= user_from_remember_token
  end

  def signed_in?
    !current_user.nil?
  end

  private

    def user_from_remember_token
      User.authenticate_with_salt(*remember_token)
    end

    def remember_token
      cookies.signed[:remember_token] || [nil, nil]
    end

Answer 1

Correct.

It’s also “splatted” (the *), meaning the return value (the cookie bits, or the [nil, nil] array if there’s no cookie) is unpacked from the array, and sent as two individual parameters (roughly) to User.authenticate_with_salt.