Added config.dependency_loading to enable or disable the dependency loader after initialization

activesupport/lib/active_support/dependencies.rb

@@ -51,17 +51,28 @@ module ActiveSupport #:nodoc:
     module ModuleConstMissing #:nodoc:
       def self.included(base) #:nodoc:
         base.class_eval do
-          # Rename the original handler so we can chain it to the new one
-          alias_method :rails_original_const_missing, :const_missing
-
-          # Use const_missing to autoload associations so we don't have to
-          # require_association when using single-table inheritance.
-          def const_missing(class_id)
-            ActiveSupport::Dependencies.load_missing_constant self, class_id
+          unless defined? const_missing_without_dependencies
+            alias_method_chain :const_missing, :dependencies
           end
         end
       end
 
+      def self.excluded(base) #:nodoc:
+        base.class_eval do
+          if defined? const_missing_without_dependencies
+            undef_method :const_missing
+            alias_method :const_missing, :const_missing_without_dependencies
+            undef_method :const_missing_without_dependencies
+          end
+        end
+      end
+
+      # Use const_missing to autoload associations so we don't have to
+      # require_association when using single-table inheritance.
+      def const_missing_with_dependencies(class_id)
+        ActiveSupport::Dependencies.load_missing_constant self, class_id
+      end
+
       def unloadable(const_desc = self)
         super(const_desc)
       end
@@ -92,8 +103,38 @@ module ActiveSupport #:nodoc:
 
     # Object includes this module
     module Loadable #:nodoc:
-      def load(file, *extras) #:nodoc:
-        Dependencies.new_constants_in(Object) { super }
+      def self.included(base) #:nodoc:
+        base.class_eval do
+          unless defined? load_without_new_constant_marking
+            alias_method_chain :load, :new_constant_marking
+          end
+        end
+      end
+
+      def self.excluded(base) #:nodoc:
+        base.class_eval do
+          if defined? load_without_new_constant_marking
+            undef_method :load
+            alias_method :load, :load_without_new_constant_marking
+            undef_method :load_without_new_constant_marking
+          end
+        end
+      end
+
+      def require_or_load(file_name)
+        Dependencies.require_or_load(file_name)
+      end
+
+      def require_dependency(file_name)
+        Dependencies.depend_on(file_name)
+      end
+
+      def require_association(file_name)
+        Dependencies.associate_with(file_name)
+      end
+
+      def load_with_new_constant_marking(file, *extras) #:nodoc:
+        Dependencies.new_constants_in(Object) { load_without_new_constant_marking(file, *extras) }
       rescue Exception => exception  # errors from loading file
         exception.blame_file! file
         raise
@@ -145,19 +186,18 @@ module ActiveSupport #:nodoc:
       end
     end
 
-    def inject!
-      Object.instance_eval do
-        define_method(:require_or_load)     { |file_name| Dependencies.require_or_load(file_name) } unless Object.respond_to?(:require_or_load)
-        define_method(:require_dependency)  { |file_name| Dependencies.depend_on(file_name) }       unless Object.respond_to?(:require_dependency)
-        define_method(:require_association) { |file_name| Dependencies.associate_with(file_name) }  unless Object.respond_to?(:require_association)
-
-        alias_method :load_without_new_constant_marking, :load
-        include Loadable
-      end
-
+    def hook!
+      Object.instance_eval { include Loadable }
       Module.instance_eval { include ModuleConstMissing }
       Class.instance_eval { include ClassConstMissing }
       Exception.instance_eval { include Blamable }
+      true
+    end
+
+    def unhook!
+      ModuleConstMissing.excluded(Module)
+      Loadable.excluded(Object)
+      true
     end
 
     def load?
@@ -560,4 +600,4 @@ module ActiveSupport #:nodoc:
   end
 end
 
-ActiveSupport::Dependencies.inject!
+ActiveSupport::Dependencies.hook!

activesupport/test/dependencies_test.rb

@@ -762,4 +762,16 @@ class DependenciesTest < Test::Unit::TestCase
   ensure
     ActiveSupport::Dependencies.load_once_paths = []
   end
+
+  def test_hook_called_multiple_times
+    assert_nothing_raised { ActiveSupport::Dependencies.hook! }
+  end
+
+  def test_unhook
+    ActiveSupport::Dependencies.unhook!
+    assert !Module.new.respond_to?(:const_missing_without_dependencies)
+    assert !Module.new.respond_to?(:load_without_new_constant_marking)
+  ensure
+    ActiveSupport::Dependencies.hook!
+  end
 end

railties/lib/initializer.rb

@@ -171,9 +171,12 @@ module Rails
       # Load view path cache
       load_view_paths
 
-      # load application classes
+      # Load application classes
       load_application_classes
 
+      # Disable dependency loading during request cycle
+      disable_dependency_loading
+
       # Flag initialized
       Rails.initialized = true
     end
@@ -525,6 +528,12 @@ Run `rake gems:install` to install the missing gems.
       Dispatcher.define_dispatcher_callbacks(configuration.cache_classes)
       Dispatcher.new(RAILS_DEFAULT_LOGGER).send :run_callbacks, :prepare_dispatch
     end
+
+    def disable_dependency_loading
+      if configuration.cache_classes && !configuration.dependency_loading
+        ActiveSupport::Dependencies.unhook!
+      end
+    end
   end
 
   # The Configuration class holds all the parameters for the Initializer and
@@ -659,6 +668,17 @@ Run `rake gems:install` to install the missing gems.
       !!@reload_plugins
     end
 
+    # Enables or disables dependency loading during the request cycle. Setting
+    # <tt>dependency_loading</tt> to true will allow new classes to be loaded
+    # during a request. Setting it to false will disable this behavior.
+    #
+    # Those who want to run in a threaded environment should disable this
+    # option and eager load or require all there classes on initialization.
+    #
+    # If <tt>cache_classes</tt> is disabled, dependency loaded will always be
+    # on.
+    attr_accessor :dependency_loading
+
     # An array of gems that this rails application depends on.  Rails will automatically load
     # these gems during installation, and allow you to install any missing gems with:
     #
@@ -707,6 +727,7 @@ Run `rake gems:install` to install the missing gems.
       self.view_path                    = default_view_path
       self.controller_paths             = default_controller_paths
       self.cache_classes                = default_cache_classes
+      self.dependency_loading           = default_dependency_loading
       self.whiny_nils                   = default_whiny_nils
       self.plugins                      = default_plugins
       self.plugin_paths                 = default_plugin_paths
@@ -876,8 +897,8 @@ Run `rake gems:install` to install the missing gems.
         paths
       end
 
-      def default_dependency_mechanism
-        :load
+      def default_dependency_loading
+        true
       end
 
       def default_cache_classes