extract formats_regexp as a method

actionpack/lib/action_view/renderer/abstract_renderer.rb

@@ -16,15 +16,18 @@ def render
     # the lookup context to take this new format into account.
     def wrap_formats(value)
       return yield unless value.is_a?(String)
-      @@formats_regexp ||= /\.(#{Mime::SET.symbols.join('|')})$/
 
-      if value.sub!(@@formats_regexp, "")
+      if value.sub!(formats_regexp, "")
         update_details(:formats => [$1.to_sym]){ yield }
       else
         yield
       end
     end
 
+    def formats_regexp
+      @@formats_regexp ||= /\.(#{Mime::SET.symbols.join('|')})$/
+    end
+
     protected
 
     def instrument(name, options={})