python核心编程-标准类派生-不可变类型

使用super

#!/usr/bin/env python# -*- coding: UTF-8 -*-class RoundFloatA(float):    def __new__(cls, val):        return float.__new__(cls, round(val, 2))class RoundFloatB(float):    def __new__(cls, val):        return super(RoundFloatB, cls).__new__(cls, round(val, 2))print RoundFloatA(1.5955)   print RoundFloatB(1.5955)

输出：

D:\Python27\test>object05.py1.61.6D:\Python27\test>