From 81b7416afa10934022ad8b1b486419d5a4ed1349 Mon Sep 17 00:00:00 2001
From: wangjohn <wangjohn@mit.edu>
Date: Mon, 18 Mar 2013 22:12:35 -0400
Subject: Removing Railtie::Configurable from the base Railtie object and
 making Railtie itself abstract. This stops the weird behavior of forcing
 subclasses of Railtie to include the Configurable module.

---
 railties/CHANGELOG.md                  |  6 +++++-
 railties/lib/rails/engine.rb           |  8 ++++----
 railties/lib/rails/railtie.rb          | 36 ++++++++++++++++++++++++++++++++--
 railties/test/railties/engine_test.rb  |  5 -----
 railties/test/railties/railtie_test.rb | 11 ++---------
 5 files changed, 45 insertions(+), 21 deletions(-)

diff --git a/railties/CHANGELOG.md b/railties/CHANGELOG.md
index ba914fb12e..e1b98eda55 100644
--- a/railties/CHANGELOG.md
+++ b/railties/CHANGELOG.md
@@ -1,3 +1,7 @@
-* No changes.
+*   Rails::Railtie no longer forces the Rails::Configurable module on everything
+    that subclassess it. Instead, the methods from Rails::Configurable have been
+    moved to class methods in Railtie and the Railtie has been made abstract.
+
+    *John Wang*
 
 Please check [4-0-stable](https://github.com/rails/rails/blob/4-0-stable/railties/CHANGELOG.md) for previous changes.
diff --git a/railties/lib/rails/engine.rb b/railties/lib/rails/engine.rb
index 86f62dfb40..94edcd352a 100644
--- a/railties/lib/rails/engine.rb
+++ b/railties/lib/rails/engine.rb
@@ -634,6 +634,10 @@ module Rails
       end
     end
 
+    def routes? #:nodoc:
+      @routes
+    end
+
     protected
 
     def run_tasks_blocks(*) #:nodoc:
@@ -641,10 +645,6 @@ module Rails
       paths["lib/tasks"].existent.sort.each { |ext| load(ext) }
     end
 
-    def routes? #:nodoc:
-      @routes
-    end
-
     def has_migrations? #:nodoc:
       paths["db/migrate"].existent.any?
     end
diff --git a/railties/lib/rails/railtie.rb b/railties/lib/rails/railtie.rb
index 9437e9c406..2b6ad1ff2d 100644
--- a/railties/lib/rails/railtie.rb
+++ b/railties/lib/rails/railtie.rb
@@ -112,7 +112,6 @@ module Rails
   # Be sure to look at the documentation of those specific classes for more information.
   #
   class Railtie
-    autoload :Configurable,  "rails/railtie/configurable"
     autoload :Configuration, "rails/railtie/configuration"
 
     include Initializable
@@ -121,6 +120,7 @@ module Rails
 
     class << self
       private :new
+      delegate :config, to: :instance
 
       def subclasses
         @subclasses ||= []
@@ -128,7 +128,6 @@ module Rails
 
       def inherited(base)
         unless base.abstract_railtie?
-          base.send(:include, Railtie::Configurable)
           subclasses << base
         end
       end
@@ -166,14 +165,47 @@ module Rails
         @railtie_name ||= generate_railtie_name(self.name)
       end
 
+      # Since Rails::Railtie cannot be instantiated, any methods that call
+      # +instance+ are intended to be called only on subclasses of a Railtie.
+      def instance
+        @instance ||= new
+      end
+
+      def respond_to_missing?(*args)
+        instance.respond_to?(*args) || super
+      end
+
+      # Allows you to configure the railtie. This is the same method seen in
+      # Railtie::Configurable, but this module is no longer required for all
+      # subclasses of Railtie so we provide the class method here.
+      def configure(&block)
+        class_eval(&block)
+      end
+
       protected
         def generate_railtie_name(class_or_module)
           ActiveSupport::Inflector.underscore(class_or_module).tr("/", "_")
         end
+
+        # If the class method does not have a method, then send the method call
+        # to the Railtie instance.
+        def method_missing(name, *args, &block)
+          if instance.respond_to?(name)
+            instance.public_send(name, *args, &block)
+          else
+            super
+          end
+        end
     end
 
     delegate :railtie_name, to: :class
 
+    def initialize
+      if self.class.abstract_railtie?
+        raise "#{self.class.name} is abstract, you cannot instantiate it directly."
+      end
+    end
+
     def config
       @config ||= Railtie::Configuration.new
     end
diff --git a/railties/test/railties/engine_test.rb b/railties/test/railties/engine_test.rb
index 01fa2c6864..0948ae59c0 100644
--- a/railties/test/railties/engine_test.rb
+++ b/railties/test/railties/engine_test.rb
@@ -416,11 +416,6 @@ YAML
       boot_rails
     end
 
-    test "Rails::Engine itself does not respond to config" do
-      boot_rails
-      assert !Rails::Engine.respond_to?(:config)
-    end
-
     test "initializers are executed after application configuration initializers" do
       @plugin.write "lib/bukkits.rb", <<-RUBY
         module Bukkits
diff --git a/railties/test/railties/railtie_test.rb b/railties/test/railties/railtie_test.rb
index 0786b8f8c7..520a855c90 100644
--- a/railties/test/railties/railtie_test.rb
+++ b/railties/test/railties/railtie_test.rb
@@ -19,8 +19,8 @@ module RailtiesTest
       @app ||= Rails.application
     end
 
-    test "Rails::Railtie itself does not respond to config" do
-      assert !Rails::Railtie.respond_to?(:config)
+    test "cannot instantiate a Railtie object" do
+      assert_raise(RuntimeError) { Rails::Railtie.new }
     end
 
     test "Railtie provides railtie_name" do
@@ -39,13 +39,6 @@ module RailtiesTest
       assert_equal "bar", Foo.railtie_name
     end
 
-    test "cannot inherit from a railtie" do
-      class Foo < Rails::Railtie ; end
-      assert_raise RuntimeError do
-        class Bar < Foo; end
-      end
-    end
-
     test "config is available to railtie" do
       class Foo < Rails::Railtie ; end
       assert_nil Foo.config.action_controller.foo
-- 
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