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
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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
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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:
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>>> runfile('F:/Python/hysrc_py/untitled0_class.py', wdir=r'F:/Python/hysrc_py')-------------------- mytime t0:__str__ hour:minute:second = 21:13:50hour:minute:second = 21:13:5021-------------------- mytime t1:hour:minute:second = 07:13:20-------------------- mydatetime da:__str__ year--mounth--day = 2016--01--01hour:minute:second = 21:40:50__del__ mydatetime destroyed>>> |
2 多重继承
2.1 定义父类 classA classX
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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
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class SubClassB(classA): def __init__(self): print('init action in subclass B') super(SubClassB,self).__init__() |
2.3 SubClassC 继承 SubClassB
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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
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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
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-------------------- SubClassC b:init action in subclass Cinit action in subclass Binit action in father class A |
3 多重继承
3.1 定义两个基本类 classA 和 classX
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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
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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
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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？
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-------------------- SubClassX x:init action in subclass Xinit action in father class ASubClassX:aSubClassX: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：
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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：
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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。
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-------------------- SubClassX x:init action in subclass Xinit action in father class ASubClassX:aTraceback (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.xAttributeError: 'SubClassX' object has no attribute 'x'>>> |
错误提示：属性错误：'SubClassX' 对象 没有属性 'x'
~~~~~~~~~~~~~~~~ 博文多为个人学习中的笔记，不保证完全正确； 参考摘录了诸多书籍，文档，仅用于学习交流 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~