ActiveSupport::Dependencies.constantize shortcut for caching named constant lookups

activesupport/lib/active_support/core_ext/string/conversions.rb

@@ -47,4 +47,15 @@ class String
     d[5] += d.pop
     ::DateTime.civil(*d)
   end
+
+  # +constantize+ tries to find a declared constant with the name specified
+  # in the string. It raises a NameError when the name is not in CamelCase
+  # or is not initialized.
+  #
+  # Examples
+  #   "Module".constantize # => Module
+  #   "Class".constantize  # => Class
+  def constantize
+    ActiveSupport::Inflector.constantize(self)
+  end
 end

activesupport/lib/active_support/core_ext/string/inflections.rb

@@ -146,15 +146,4 @@ class String
   def foreign_key(separate_class_name_and_id_with_underscore = true)
     ActiveSupport::Inflector.foreign_key(self, separate_class_name_and_id_with_underscore)
   end
-
-  # +constantize+ tries to find a declared constant with the name specified
-  # in the string. It raises a NameError when the name is not in CamelCase
-  # or is not initialized.
-  #
-  # Examples
-  #   "Module".constantize # => Module
-  #   "Class".constantize  # => Class
-  def constantize
-    ActiveSupport::Inflector.constantize(self)
-  end
 end

activesupport/lib/active_support/dependencies.rb

@@ -484,8 +484,10 @@ module ActiveSupport #:nodoc:
     end
 
     class Reference
-      def initialize(constant, name)
-        @constant, @name = constant, name
+      attr_reader :name
+
+      def initialize(name, constant = nil)
+        @name, @constant = name, constant
       end
 
       def get
@@ -498,7 +500,11 @@ module ActiveSupport #:nodoc:
     end
 
     def ref(name)
-      references[name] ||= Reference.new(Inflector.constantize(name), name)
+      references[name] ||= Reference.new(name)
+    end
+
+    def constantize(name)
+      ref(name).get
     end
 
     # Determine if the given constant has been automatically loaded.

activesupport/test/dependencies_test.rb

@@ -446,6 +446,12 @@ class DependenciesTest < Test::Unit::TestCase
     end
   end
 
+  def test_constantize_shortcut_for_cached_constant_lookups
+    with_loading 'dependencies' do
+      assert_equal ServiceOne, ActiveSupport::Dependencies.constantize("ServiceOne")
+    end
+  end
+
   def test_nested_load_error_isnt_rescued
     with_loading 'dependencies' do
       assert_raise(MissingSourceFile) do