instance method compile

# File activesupport/lib/active_support/callbacks.rb, line 351
      def compile(key=nil, object=nil)
        method = []
        method << "value = nil"
        method << "halted = false"

        each do |callback|
          method << callback.start(key, object)
        end

        if config[:rescuable]
          method << "rescued_error = nil"
          method << "begin"
        end

        method << "value = yield if block_given? && !halted"

        if config[:rescuable]
          method << "rescue Exception => e"
          method << "rescued_error = e"
          method << "end"
        end

        reverse_each do |callback|
          method << callback.end(key, object)
        end

        method << "raise rescued_error if rescued_error" if config[:rescuable]
        method << "halted ? false : (block_given? ? value : true)"
        method.compact.join("\n")
      end