Merge pull request #8557 from timraymond/add_back_engines_and_deprecate

Adding Back Rails::Engine::Railties#engines

Conflicts:
	railties/CHANGELOG.md

3 files changed, 34 insertions, 5 deletions

diff --git a/railties/lib/rails/application.rb b/railties/lib/rails/application.rb
index cff75872b2..05cc49d40a 100644
--- a/railties/lib/rails/application.rb
+++ b/railties/lib/rails/application.rb
@@ -55,6 +55,7 @@ module Rails
     autoload :Bootstrap,      'rails/application/bootstrap'
     autoload :Configuration,  'rails/application/configuration'
     autoload :Finisher,       'rails/application/finisher'
+    autoload :Railties,       'rails/engine/railties'
     autoload :RoutesReloader, 'rails/application/routes_reloader'
 
     class << self
@@ -232,11 +233,6 @@ module Rails
       config.helpers_paths
     end
 
-    def railties #:nodoc:
-      @railties ||= Rails::Railtie.subclasses.map(&:instance) +
-        Rails::Engine.subclasses.map(&:instance)
-    end
-
   protected
 
     alias :build_middleware_stack :app
diff --git a/railties/lib/rails/engine.rb b/railties/lib/rails/engine.rb
index 0ae2f16aba..46a6485c44 100644
--- a/railties/lib/rails/engine.rb
+++ b/railties/lib/rails/engine.rb
@@ -466,6 +466,10 @@ module Rails
       end
     end
 
+    def railties
+      @railties ||= self.class::Railties.new
+    end
+
     # Returns a module with all the helpers defined for the engine.
     def helpers
       @helpers ||= begin
diff --git a/railties/lib/rails/engine/railties.rb b/railties/lib/rails/engine/railties.rb
new file mode 100644
index 0000000000..1081700cd0
--- /dev/null
+++ b/railties/lib/rails/engine/railties.rb
@@ -0,0 +1,29 @@
+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 self.engines
+        @engines ||= ::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
+
+ActiveSupport::Deprecation.deprecate_methods(Rails::Engine::Railties, :engines)