python 類定義 繼承
阿新 • • 發佈：2018-02-25
src body 默認 father 系統 intel minute 調用 lshell
0 前言
系統：win7 64bit
IDE ： python(x,y) 2.7.6.1
IDE集成的解釋器：Python 2.7.6 (default, Nov 10 2013, 19:24:18) [MSC v.1500 32 bit (Intel)] on win32
1 單繼承
1.1 定義一個時間類，帶默認參數
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)
說明： 構造函數 __init__(self,hour=21, minute=13, second=50) 帶默認參數的定義方式 ；
用於輸出的函數 __str__
得到某屬性值的方法 get_xxxx
輸出屬性值的方法 print_time
1.2 定義日期時間類，繼承時間類的屬性和方法
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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()
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說明： mydatetime 繼承 mytime 的屬性值，這裏mydatetime（子類），mytime（父類）
構造函數 __init__(self,year = 2016,mounth = 1,day = 1, hour=21, minute=13,second=50) 帶默認參數的定義方式 ，註意要通過 super初始化父類屬性值；
用於輸出的函數 __str__
輸出屬性值的方法 print_date
1.3 測試
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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
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輸出:
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>>> runfile(‘F:/Python/hysrc_py/untitled0_class.py‘, wdir=r‘F:/Python/hysrc_py‘)
-------------------- mytime t0:
__str__ hour:minute:second = 21:13:50
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 多重繼承
2.1 定義父類 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 繼承 classA
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class SubClassB(classA):
def __init__(self):
print(‘init action in subclass B‘)
super(SubClassB,self).__init__()
|
2.3 SubClassC 繼承 SubClassB
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class SubClassC(SubClassB):
def __init__(self):
print(‘init action in subclass C‘)
super(SubClassC,self).__init__()
|
2.4 測試
實例化一個SubClassC類
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if __name__ == ‘__main__‘:
print "\n"
print "--"*10," SubClassC b:"
b = SubClassC()
|
由輸出可知：多重繼承時，子類會自動調用父類的構造函數
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-------------------- SubClassC b:
init action in subclass C
init action in subclass B
init action in father class A
|
3 多重繼承
3.1 定義兩個基本類 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 類繼承自 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()
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3.3 實例化一個 SubClassX 類
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if __name__ == ‘__main__‘:
print "\n"
print "--"*10," SubClassX x:"
sx = SubClassX()
sx.print_SubX()
|
3.4 由輸出可知 ： SubClassX 繼承了 classA 和 classX 的方法和屬性，但不知為何只調用了 classA的初始化函數？
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-------------------- SubClassX x:
init action in subclass X
init action in father class A
SubClassX:a
SubClassX:x
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3.5 分析：其實在 3.4 的輸出可知，SubClassX只調用了classA的初始化，則classX的屬性是不會自動初始化的，如classX的屬性值x，之所以能夠輸出 "SubClassX:x" ,是由於在 3.2的定義中，手動初試化了 屬性值。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()
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實例化一個 SubClassX 類：
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if __name__ == ‘__main__‘:
print "\n"
print "--"*10," SubClassX x:"
sx = SubClassX()
sx.print_SubX()
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輸出報錯： 由於定義SubClassX類時，使用 super 初始化父類，只會初試化 classA，即第一個類。而classX排在了classA之後，不會自動初始化。所以在實例化類調用方法時，即 sx.print_SubX() 。由於沒有屬性 ‘x‘ 而報錯。
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-------------------- 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:\Python27\lib\site-packages\spyderlib\widgets\externalshell\sitecustomize.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‘
>>>
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錯誤提示：屬性錯誤：‘SubClassX‘ 對象 沒有屬性 ‘x‘
python 類定義 繼承