Deprecate handler_class_for_extension as template handlers can be any Ruby object, not necessarily a class.

actionpack/lib/action_view/renderer/template_renderer.rb

@@ -45,7 +45,7 @@ module ActionView
       elsif options.key?(:file)
         with_fallbacks { find_template(options[:file], options[:prefix], false, keys) }
       elsif options.key?(:inline)
-        handler = Template.handler_class_for_extension(options[:type] || "erb")
+        handler = Template.handler_for_extension(options[:type] || "erb")
         Template.new(options[:inline], "inline template", handler, :locals => keys)
       elsif options.key?(:template)
         options[:template].respond_to?(:render) ?

actionpack/lib/action_view/template/handlers.rb

@@ -44,7 +44,13 @@ module ActionView #:nodoc:
       end
 
       def handler_class_for_extension(extension)
-        (extension && registered_template_handler(extension.to_sym)) || @@default_template_handlers
+        ActiveSupport::Deprecation.warn "handler_class_for_extension is deprecated. " <<
+          "Please use handler_for_extension instead", caller
+        handler_for_extension(extension)
+      end
+
+      def handler_for_extension(extension)
+        registered_template_handler(extension) || @@default_template_handlers
       end
     end
   end

actionpack/lib/action_view/template/resolver.rb

@@ -129,7 +129,7 @@ module ActionView
     def extract_handler_and_format(path, default_formats)
       pieces = File.basename(path).split(".")
       pieces.shift
-      handler = Template.handler_class_for_extension(pieces.pop)
+      handler = Template.handler_for_extension(pieces.pop)
       format  = pieces.last && Mime[pieces.last]
       [handler, format]
     end