# File lib/active_record/observer.rb, line 34 def instantiate_observers return if @observers.blank? @observers.each do |observer| if observer.respond_to?(:to_sym) # Symbol or String observer.to_s.camelize.constantize.instance elsif observer.respond_to?(:instance) observer.instance else raise ArgumentError, "#{observer} must be a lowercase, underscored class name (or an instance of the class itself) responding to the instance method. Example: Person.observers = :big_brother # calls BigBrother.instance" end end end