python 类定义 继承

1 定义一个时间类，带默认参数

class mytime(object):
    def __init__(self,hour=21,                  minute=13,                  second=50):
        self.hour   = hour
        self.minute = minute
        self.second = second

    def __str__(self):
        return ‘__str__ hour:minute:second = %02d:%02d:%02d‘                %(self.hour,self.minute,self.second)

    def get_hour(self):
        return self.hour

    def get_minute(self):
        return self.minute

    def get_second(self):
        return self.second

    def print_time(self):
        print  ‘hour:minute:second = %02d:%02d:%02d‘ %(self.hour,self.minute,self.second)
  

说明：  构造函数     __init__(self,hour=21, minute=13, second=50)  带默认参数的定义方式 ；

　　　  用于输出的函数    __str__

得到某属性值的方法    get_xxxx

输出属性值的方法 print_time

2 定义日期时间类，继承时间类的属性和方法

class mydatetime(mytime):
    def __init__(self,year = 2016,mounth = 1,day = 1,                       hour=21, minute=13,second=50):
        super(mydatetime,self).__init__(hour,minute,second)
        self.year = year
        self.mounth = mounth
        self.day = day

    def __str__(self):
        return ‘__str__ year--mounth--day = %02d--%02d--%02d‘                %(self.year,self.mounth,self.day)

    def __del__(self):
        """ __del__ mydatetime destroyed """
        print "__del__ mydatetime destroyed"

    def print_date(self):
        print  ‘year-mounth-day = %04d-%02d-%02d‘         %(self.year,self.mounth,self.day)
#        self.print_time()

说明：   mydatetime 继承 mytime 的属性值，这里mydatetime（子类），mytime（父类）

　　  构造函数     __init__(self,year = 2016,mounth = 1,day = 1, hour=21, minute=13,second=50)  带默认参数的定义方式 ，注意要通过 super初始化父类属性值；

　　  用于输出的函数    __str__

输出属性值的方法 print_date

3 测试

if __name__ == ‘__main__‘:

    print "\n"
    print "--"*10," mytime t0:"
    t0 = mytime()
    print t0
    t0.print_time()
    print t0.get_hour()

    print "\n"
    print "--"*10," mytime t1:"
    t1 = mytime(hour=7,second=20)
    t1.print_time()

    print "\n"
    print "--"*10," mydatetime da:"
    da = mydatetime(minute=40)
    print da
#    da.print_date()
    da.print_time()
    del da

测试输出

>>> runfile(‘F:/Python/hysrc_py/untitled0_class.py‘, wdir=r‘F:/Python/hysrc_py‘)

--------------------  mytime t0:
__str__ hour:minute:second = 21:13:50
hour:minute:second = 21:13:50
21

--------------------  mytime t1:
hour:minute:second = 07:13:20

--------------------  mydatetime da:
__str__ year--mounth--day = 2016--01--01
hour:minute:second = 21:40:50
__del__ mydatetime destroyed
>>>