0 前言
系统：win7 64bit
IDE ： python(x,y) 2.7.6.1
IDE集成的解释器：Python 2.7.6 (default, Nov 10 2013, 19:24:18) [MSC v.1500 32 bit (Intel)] on win32
1 单继承
1.1 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
1.2 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
1.3 测试
if __name__ == '__main__':
print "
"
print "--"*10," mytime t0:"
t0 = mytime()
print t0
t0.print_time()
print t0.get_hour()
print "
"
print "--"*10," mytime t1:"
t1 = mytime(hour=7,second=20)
t1.print_time()
print "
"
print "--"*10," mydatetime da:"
da = mydatetime(minute=40)
print da
# da.print_date()
da.print_time()
del da
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
>>>
2 多重继承
2.1 定义父类 classA classX
class classA(object):
def __init__(self):
print('init action in father class A')
class classX(object):
def __init__(self):
print('init action in father class X')
2.2 SubClassB 继承 classA
class SubClassB(classA):
def __init__(self):
print('init action in subclass B')
super(SubClassB,self).__init__()
2.3 SubClassC 继承 SubClassB
class SubClassC(SubClassB):
def __init__(self):
print('init action in subclass C')
super(SubClassC,self).__init__()
2.4 测试
实例化一个SubClassC类
if __name__ == '__main__':
print "
"
print "--"*10," SubClassC b:"
b = SubClassC()
由输出可知：多重继承时，子类会自动调用父类的构造函数
-------------------- SubClassC b: init action in subclass C init action in subclass B init action in father class A
3 多重继承
3.1 定义两个基本类 classA 和 classX
class classA(object):
def __init__(self,a='classA'):
self.a = a
print('init action in father class A')
def print_a(self):
print self.a
class classX(object):
def __init__(self,x='classX'):
self.x = x
print('init action in father class X')
def print_x(self):
print self.x
3.2 SubClassX 类继承自 classA 和 classX
class SubClassX(classA,classX):
def __init__(self,a='SubClassX:a',x='SubClassX:x'):
print('init action in subclass X')
super(SubClassX,self).__init__()
# classX.__init__(self)
self.a = a
self.x = x
def print_SubX(self):
self.print_a()
self.print_x()
3.3 实例化一个 SubClassX 类
if __name__ == '__main__':
print "
"
print "--"*10," SubClassX x:"
sx = SubClassX()
sx.print_SubX()
3.4 由输出可知 ： SubClassX 继承了 classA 和 classX 的方法和属性，但不知为何只调用了 classA的初始化函数？
-------------------- SubClassX x: init action in subclass X init action in father class A SubClassX:a SubClassX:x
3.5 分析：其实在 3.4 的输出可知，SubClassX只调用了classA的初始化，则classX的属性是不会自动初始化的，如classX的属性值x，之所以能够输出 "SubClassX:x" ,是由于在 3.2的定义中，手动初试化了 属性值。self.a = a self.x = x
如下例：
class SubClassX(classA,classX):
def __init__(self,a='SubClassX:a',x='SubClassX:x'):
print('init action in subclass X')
super(SubClassX,self).__init__(a)
# classX.__init__(self)
# self.x = x
def print_SubX(self):
self.print_a()
self.print_x()
实例化一个 SubClassX 类：
if __name__ == '__main__':
print "
"
print "--"*10," SubClassX x:"
sx = SubClassX()
sx.print_SubX()
输出报错： 由于定义SubClassX类时，使用 super 初始化父类，只会初试化 classA，即第一个类。而classX排在了classA之后，不会自动初始化。所以在实例化类调用方法时，即 sx.print_SubX() 。由于没有属性 'x' 而报错。
-------------------- SubClassX x:
init action in subclass X
init action in father class A
SubClassX:a
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "C:Python27libsite-packagesspyderlibwidgetsexternalshellsitecustomize.py", line 540, in runfile
execfile(filename, namespace)
File "F:/Python/hysrc_py/untitled0_class.py", line 111, in <module>
sx.print_SubX()
File "F:/Python/hysrc_py/untitled0_class.py", line 57, in print_SubX
self.print_x()
File "F:/Python/hysrc_py/untitled0_class.py", line 24, in print_x
print self.x
AttributeError: 'SubClassX' object has no attribute 'x'
>>>
错误提示：属性错误：'SubClassX' 对象 没有属性 'x'