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
"\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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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
:
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
>>>
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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'
)
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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__()
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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__()
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2.4 测试
实例化一个SubClassC类
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if
__name__
=
=
'__main__'
:
print
"\n"
print
"--"
*
10
,
" SubClassC b:"
b
=
SubClassC()
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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 C
init action
in
subclass B
init action
in
father
class
A
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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
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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()
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3.3 实例化一个 SubClassX 类
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if
__name__
=
=
'__main__'
:
print
"\n"
print
"--"
*
10
,
" SubClassX x:"
sx
=
SubClassX()
sx.print_SubX()
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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 X
init action
in
father
class
A
SubClassX:a
SubClassX:x
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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()
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实例化一个 SubClassX 类：
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if
__name__
=
=
'__main__'
:
print
"\n"
print
"--"
*
10
,
" SubClassX x:"
sx
=
SubClassX()
sx.print_SubX()
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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 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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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 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~