add_association_callbacks

# File activerecord/lib/active_record/associations.rb, line 1035
        def add_association_callbacks(association_name, options)
          callbacks = %w(before_add after_add before_remove after_remove)
          callbacks.each do |callback_name|
            full_callback_name = "#{callback_name.to_s}_for_#{association_name.to_s}"
            defined_callbacks = options[callback_name.to_sym]
            if options.has_key?(callback_name.to_sym)
              class_inheritable_reader full_callback_name.to_sym
              write_inheritable_array(full_callback_name.to_sym, [defined_callbacks].flatten)
            end
          end
        end