Ability - cancan abstract resource authorization

ability.rb

class Ability
  include CanCan::Ability

  def initialize(user)
    user ||= User.new

    resourceful_actions = [
      :index,
      :show,
      :new,
      :create,
      :edit,
      :update,
      :destroy
    ]

    cannot resourceful_actions, User
    can :update, User, :id => user.id
  end

end