--- attr(name[, assignable])

    °ɤ߹ߤΤΥ󥹥󥹥᥽å name ޤ
    name  Symbol ʸǻꤷޤͤϾ
    nil Ǥ

    Υ᥽åɤ륢᥽åɤϼ̤Ǥ

      def name
        @name
      end

    άǽ 2  assignable ꤵ줽ͤǤ
    ˤϡ°ν񤭤ѥ᥽å name= Ʊޤ
    ϼ̤Ǥ

      def name=(val)
        @name = val
      end

