2 files changed, 135 insertions, 0 deletions
diff --git a/railties/lib/rails/railtie/configurable.rb b/railties/lib/rails/railtie/configurable.rb
new file mode 100644
index 0000000000..1572af0b2a
--- /dev/null
+++ b/railties/lib/rails/railtie/configurable.rb
@@ -0,0 +1,35 @@
+require 'active_support/concern'
+
+module Rails
+  class Railtie
+    module Configurable
+      extend ActiveSupport::Concern
+
+      module ClassMethods
+        delegate :config, to: :instance
+
+        def inherited(base)
+          raise "You cannot inherit from a #{self.superclass.name} child"
+        end
+
+        def instance
+          @instance ||= new
+        end
+
+        def respond_to?(*args)
+          super || instance.respond_to?(*args)
+        end
+
+        def configure(&block)
+          class_eval(&block)
+        end
+
+        protected
+
+        def method_missing(*args, &block)
+          instance.send(*args, &block)
+        end
+      end
+    end
+  end
+end
diff --git a/railties/lib/rails/railtie/configuration.rb b/railties/lib/rails/railtie/configuration.rb
new file mode 100644
index 0000000000..eb3b2d8ef4
--- /dev/null
+++ b/railties/lib/rails/railtie/configuration.rb
@@ -0,0 +1,100 @@
+require 'rails/configuration'
+
+module Rails
+  class Railtie
+    class Configuration
+      def initialize
+        @@options ||= {}
+      end
+
+      # Expose the eager_load_namespaces at "module" level for convenience.
+      def self.eager_load_namespaces #:nodoc:
+        @@eager_load_namespaces ||= []
+      end
+
+      # All namespaces that are eager loaded
+      def eager_load_namespaces
+        @@eager_load_namespaces ||= []
+      end
+
+      # Add files that should be watched for change.
+      def watchable_files
+        @@watchable_files ||= []
+      end
+
+      # Add directories that should be watched for change.
+      # The key of the hashes should be directories and the values should
+      # be an array of extensions to match in each directory.
+      def watchable_dirs
+        @@watchable_dirs ||= {}
+      end
+
+      # This allows you to modify the application's middlewares from Engines.
+      #
+      # All operations you run on the app_middleware will be replayed on the
+      # application once it is defined and the default_middlewares are
+      # created
+      def app_middleware
+        @@app_middleware ||= Rails::Configuration::MiddlewareStackProxy.new
+      end
+
+      # This allows you to modify application's generators from Railties.
+      #
+      # Values set on app_generators will become defaults for application, unless
+      # application overwrites them.
+      def app_generators
+        @@app_generators ||= Rails::Configuration::Generators.new
+        yield(@@app_generators) if block_given?
+        @@app_generators
+      end
+
+      # First configurable block to run. Called before any initializers are run.
+      def before_configuration(&block)
+        ActiveSupport.on_load(:before_configuration, yield: true, &block)
+      end
+
+      # Third configurable block to run. Does not run if +config.cache_classes+
+      # set to false.
+      def before_eager_load(&block)
+        ActiveSupport.on_load(:before_eager_load, yield: true, &block)
+      end
+
+      # Second configurable block to run. Called before frameworks initialize.
+      def before_initialize(&block)
+        ActiveSupport.on_load(:before_initialize, yield: true, &block)
+      end
+
+      # Last configurable block to run. Called after frameworks initialize.
+      def after_initialize(&block)
+        ActiveSupport.on_load(:after_initialize, yield: true, &block)
+      end
+
+      # Array of callbacks defined by #to_prepare.
+      def to_prepare_blocks
+        @@to_prepare_blocks ||= []
+      end
+
+      # Defines generic callbacks to run before #after_initialize. Useful for
+      # Rails::Railtie subclasses.
+      def to_prepare(&blk)
+        to_prepare_blocks << blk if blk
+      end
+
+      def respond_to?(name, include_private = false)
+        super || @@options.key?(name.to_sym)
+      end
+
+    private
+
+      def method_missing(name, *args, &blk)
+        if name.to_s =~ /=$/
+          @@options[$`.to_sym] = args.first
+        elsif @@options.key?(name)
+          @@options[name]
+        else
+          super
+        end
+      end
+    end
+  end
+end