start

# File activesupport/lib/active_support/callbacks.rb, line 171
      def start(key=nil, object=nil)
        return if key && !object.send("_one_time_conditions_valid_#{@callback_id}?")

        # options[0] is the compiled form of supplied conditions
        # options[1] is the "end" for the conditional
        #
        case @kind
        when :before
          # if condition    # before_save :filter_name, :if => :condition
          #   filter_name
          # end
                      if !halted && #{@compiled_options}              # This double assignment is to prevent warnings in 1.9.3 as              # the `result` variable is not always used except if the              # terminator code refers to it.              result = result = #{@filter}              halted = (#{chain.config[:terminator]})              if halted                halted_callback_hook(#{@raw_filter.inspect.inspect})              end            end
        when :around
          # Compile around filters with conditions into proxy methods
          # that contain the conditions.
          #
          # For `around_save :filter_name, :if => :condition':
          #
          # def _conditional_callback_save_17
          #   if condition
          #     filter_name do
          #       yield self
          #     end
          #   else
          #     yield self
          #   end
          # end
          #
          name = "_conditional_callback_#{@kind}_#{next_id}"
          @klass.class_eval              def #{name}(halted)              if #{@compiled_options} && !halted                #{@filter} do                  yield self                end              else                yield self              end            end,  __FILE__, __LINE__ + 1
          "#{name}(halted) do"
        end
      end