一个关于python定制类的例子

class Time(object):
    def __init__(self, hr, min):
        self.hr = hr
        self.min = min

    def __str__(self):
        return ‘%d:%d‘ %(self.hr, self.min)

    __repr__ = __str__

    # 重载加法
    def __add__(self, other):
        m = self.min + other.min
        h = self.hr + other.hr
        if m>=60:
            m -= 60
            h += 1
        if h>=24:
            h -= 24
        return self.__class__(h, m)

    # 重载‘+=‘方法
    def __iadd__(self, other):
        self.hr += other.hr
        self.min += other.min
        if self.min >= 60:
            self.min -= 60
            self.hr += 1
        if self.hr >=24:
            self.hr -= 24
        return self