Compile ActionController::Base.config's methods to avoid method_missing overhead.

actionpack/lib/action_controller/railtie.rb

@@ -26,6 +26,10 @@ class Railtie < Rails::Railtie
       options.stylesheets_dir      ||= paths.public.stylesheets.to_a.first
       options.page_cache_directory ||= paths.public.to_a.first
 
+      # make sure readers methods get compiled
+      options.asset_path           ||= nil
+      options.asset_host           ||= nil
+
       ActiveSupport.on_load(:action_controller) do
         include app.routes.mounted_helpers
         extend ::AbstractController::Railties::RoutesHelpers.with(app.routes)
@@ -33,5 +37,11 @@ class Railtie < Rails::Railtie
         options.each { |k,v| send("#{k}=", v) }
       end
     end
+
+    config.after_initialize do
+      ActiveSupport.on_load(:action_controller) do
+        config.crystalize! if config.respond_to?(:crystalize!)
+      end
+    end
   end
 end

actionpack/lib/action_view/base.rb

@@ -209,8 +209,7 @@ def initialize(lookup_context = nil, assigns_for_first_render = {}, controller =
         @_request = controller.request if controller.respond_to?(:request)
       end
 
-      config = controller && controller.respond_to?(:config) ? controller.config : {}
-      @_config = ActiveSupport::InheritableOptions.new(config)
+      @_config = controller && controller.respond_to?(:config) ? controller.config.inheritable_copy : {}
 
       @_content_for  = Hash.new { |h,k| h[k] = ActiveSupport::SafeBuffer.new }
       @_virtual_path = nil

activesupport/lib/active_support/configurable.rb

@@ -9,9 +9,29 @@ module ActiveSupport
   module Configurable
     extend ActiveSupport::Concern
 
+    class Configuration < ActiveSupport::InheritableOptions
+      def crystalize!
+        self.class.crystalize!(keys.reject {|key| respond_to?(key)})
+      end
+
+      # compiles reader methods so we don't have to go through method_missing
+      def self.crystalize!(keys)
+        keys.each do |key|
+          class_eval <<-RUBY, __FILE__, __LINE__ + 1
+            def #{key}; self[#{key.inspect}]; end
+          RUBY
+        end
+      end
+    end
+
     module ClassMethods
       def config
-        @_config ||= ActiveSupport::InheritableOptions.new(superclass.respond_to?(:config) ? superclass.config : {})
+        @_config ||= if superclass.respond_to?(:config)
+          superclass.config.inheritable_copy
+        else
+          # create a new "anonymous" class that will host the compiled reader methods
+          Class.new(Configuration).new({})
+        end
       end
 
       def configure
@@ -48,7 +68,7 @@ def #{name}=(value); config.#{name} = value; end
     #   user.config.level          # => 1
     # 
     def config
-      @_config ||= ActiveSupport::InheritableOptions.new(self.class.config)
+      @_config ||= self.class.config.inheritable_copy
     end
   end
 end

activesupport/lib/active_support/ordered_options.rb

@@ -39,5 +39,9 @@ class InheritableOptions < OrderedOptions
     def initialize(parent)
       super() { |h,k| parent[k] }
     end
+
+    def inheritable_copy
+      self.class.new(self)
+    end
   end
 end

activesupport/test/configurable_test.rb

@@ -39,4 +39,22 @@ class Child < Parent
     assert_equal :baz, instance.config.foo
     assert_equal :bar, Parent.config.foo
   end
+
+  test "configuration is crystalizeable" do
+    parent = Class.new { include ActiveSupport::Configurable }
+    child  = Class.new(parent)
+
+    parent.config.bar = :foo
+    assert !parent.config.respond_to?(:bar)
+    assert !child.config.respond_to?(:bar)
+    assert !child.new.config.respond_to?(:bar)
+
+    parent.config.crystalize!
+    assert_equal :foo, parent.config.bar
+    assert_equal :foo, child.new.config.bar
+
+    assert_respond_to parent.config, :bar
+    assert_respond_to child.config, :bar
+    assert_respond_to child.new.config, :bar
+  end
 end
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