python的继承

• 首先参考这篇文章：http://www.jb51.net/article/100195.htm

[root@shuffle-dev py_test]$ vim sf_nameMangling.py 
#!/usr/bin/env python
# -*- coding: utf-8 -*-

class A(object):
    def __init__(self):
        self.__private()
        self.public()
    def __private(self):
        print 'A.private()'
    def public(self):
        print 'A.public'
class B(A):
    def __private(self):
        print 'B.private()'
    def public(self):
        print 'B.public'
class C(A):
    def __init__(self):
        self.__private()
        self.public()
    @classmethod
    def __private(cls):
        print 'C.private'
    @staticmethod
    def public():
        print 'public'

print '---create b---'
b=B()
print '---create c---'
c=C()
print '---method of class C---'
C._C__private()
C.public()   

• 然而如下代码会遇到：NameError: global name 'typecode' is not defined
  这里可以参考：http://python.jobbole.com/85100/

[root@shuffle-dev py_test]$ vim sf_classextend.py
#!/usr/bin/env python
# -*- coding: utf-8 -*-
#Author:xushuffle
import sys
reload(sys)
sys.setdefaultencoding('utf-8')

from array import array

class base(object):
    def __init__(self,x,y):
        self.x,self.y=x,y
    def echo(self):
        print self.x,self.y

class sub(base):
    typecode='d'
    def __init__(self,components):
        self.components=array(typecode,components)

# s=sub(range(5))
# s.echo()

class sub2(base):
    typecode='d'
    def __init__(self,components):
        self.x,self.y=components[0],components[1]
        self.components=array(self.typecode,components)

s=sub2(range(5))                                                                                                                              
s.echo()

• python作为动态语言和java等静态语言的行为不太一致

[root@shuffle-dev py_test]$ python
Python 2.6.6 (r266:84292, Jul 10 2013, 22:48:45) 
[GCC 4.4.7 20120313 (Red Hat 4.4.7-3)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> from sf_classextend import sub
0 1
>>> from dis import dis
>>> dis(sub)
Disassembly of __init__:
 19           0 LOAD_GLOBAL              0 (array)
              3 LOAD_GLOBAL              1 (typecode)
              6 LOAD_FAST                1 (components)
              9 CALL_FUNCTION            2
             12 LOAD_FAST                0 (self)
             15 STORE_ATTR               2 (components)
             18 LOAD_CONST               0 (None)
             21 RETURN_VALUE        

>>> 

dis模块的参考文档在这里：https://docs.python.org/2/library/dis.html
typecode是从global里面load的
例如
LOAD_FAST(var_num)
Pushes a reference to the local co_varnames[var_num] onto the stack.

• co_varnames是什么呢？
  参考：https://www.jianshu.com/p/649ba6219d06

[root@shuffle-dev py_test]$ python
Python 2.6.6 (r266:84292, Jul 10 2013, 22:48:45) 
[GCC 4.4.7 20120313 (Red Hat 4.4.7-3)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> f=open('sf_classextend.py','r').read()
>>> co=compile(f,'sf_classextend.sub','exec')
>>> print co.co_varnames
()
>>> print co.co_names
('sys', 'reload', 'setdefaultencoding', 'array', 'object', 'base', 'sub', 'sub2', 'range', 's', 'echo')
>>> print co.co_consts
(-1, None, 'utf-8', ('array',), 'base', <code object base at 0x2aaed06c64e0, file "sf_classextend.sub", line 10>, 'sub', <code object sub at 0x2aaed06cd120, file "sf_classextend.sub", line 16>, 'sub2', <code object sub2 at 0x2aaed06d7738, file "sf_classextend.sub", line 24>, 5)
>>>