module Rails class Engine < Railtie class Railties include Enumerable attr_reader :_all def initialize @_all ||= ::Rails::Railtie.subclasses.map(&:instance) + ::Rails::Engine.subclasses.map(&:instance) end def each(*args, &block) _all.each(*args, &block) end def -(others) _all - others end delegate :engines, to: "self.class" end end end