def _define_before_model_callback(klass, callback) #:nodoc:
  klass.class_eval <<-CALLBACK, __FILE__, __LINE__ + 1
    def self.before_#{callback}(*args, &block)
      set_callback(:#{callback}, :before, *args, &block)
    end
  CALLBACK
end

def _define_around_model_callback(klass, callback) #:nodoc:
  klass.class_eval <<-CALLBACK, __FILE__, __LINE__ + 1
    def self.around_#{callback}(*args, &block)
      set_callback(:#{callback}, :around, *args, &block)
    end
  CALLBACK
end

def _define_after_model_callback(klass, callback) #:nodoc:
  klass.class_eval <<-CALLBACK, __FILE__, __LINE__ + 1
    def self.after_#{callback}(*args, &block)
      options = args.extract_options!
      options[:prepend] = true
      options[:if] = Array.wrap(options[:if]) << "!halted && value != false"
      set_callback(:#{callback}, :after, *(args << options), &block)
    end
  CALLBACK
end