1 files changed, 21 insertions, 0 deletions
diff --git a/railties/lib/rails/engine/railties.rb b/railties/lib/rails/engine/railties.rb
new file mode 100644
index 0000000000..9969a1475d
--- /dev/null
+++ b/railties/lib/rails/engine/railties.rb
@@ -0,0 +1,21 @@
+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
+    end
+  end
+end