Add the ability to prepend filters to new callbacks

actionpack/lib/action_controller/abstract/callbacks.rb

@@ -37,6 +37,15 @@ def #{filter}_filter(*names, &blk)
             end
           end
 
+          def prepend_#{filter}_filter(*names, &blk)
+            options = names.last.is_a?(Hash) ? names.pop : {}
+            _normalize_callback_options(options)
+            names.push(blk) if block_given?
+            names.each do |name|
+              process_action_callback(:#{filter}, name, options.merge(:prepend => true))
+            end
+          end
+
           def skip_#{filter}_filter(*names, &blk)
             options = names.last.is_a?(Hash) ? names.pop : {}
             _normalize_callback_options(options)

activesupport/lib/active_support/new_callbacks.rb

@@ -464,7 +464,9 @@ def self.#{symbol}_callback(*filters, &blk)
                 self._#{symbol}_callbacks.delete_if {|c| c.matches?(type, :#{symbol}, filter)}
                 Callback.new(filter, type, options.dup, self, :#{symbol})
               end
-              self._#{symbol}_callbacks.push(*filters)
+              options[:prepend] ?
+                self._#{symbol}_callbacks.unshift(*filters) :
+                self._#{symbol}_callbacks.push(*filters)
               _define_runner(:#{symbol}, 
                 self._#{symbol}_callbacks.compile(nil, :terminator => _#{symbol}_terminator), 
                 options)