    # File lib/active_support/core_ext/module/attr_accessor_with_default.rb, line 21
      def attr_accessor_with_default(sym, default = nil, &block)
        raise 'Default value or block required' unless !default.nil? || block
        define_method(sym, block_given? ? block : Proc.new { default })
        module_eval("def \#{sym}=(value)\nclass << self; attr_reader :\#{sym} end\n@\#{sym} = value\nend\n", __FILE__, __LINE__)
      end