Python2.7继承使用super初始化父类

本文只关注２.x的父类构造，因为3.0以后机制又变了。这里有两个class，Person和Student：
person.py

#!/usr/bin/python  
# -*- coding: UTF-8 -*-  
class Person(object):  
    def __init__(self, sex):  
        self.sex = sex  
  
    def showSex(self):  
        print self.sex

然后是stu.py继承Person

# --*coding:utf8 *--  
from com.gxf.entity.person import Person  
  
  
class Student(Person):  
    '提供对学生的操作'  
    stuCount = 0  
  
    def __init__(self, name="unkonwn", age=20, sex="男"):  
        # Person.__init__(self,sex)  
        super(Student, self).__init__(sex)  
        self.name = name  
        self.age = age  
        Student.stuCount += 1  
  
    def displayStuCount(self):  
        print "Total student is :%d" % Student.stuCount  
  
    def __test(self):  
        print "inner method"  
  
    def displayStu(self):  
        self.__test()  
        print "Name: ", self.name, "age: ", self.age  
  
  
if __name__ == "__main__":  
    stu = Student("gongxufan", 30, "男");  
    stu.displayStu();  
    stu.displayStuCount();  
    stu.showSex()

在子类的init中调用父类构造有两种方式：

• 一种是用父类名去调用

  Person.__init__(self,sex)

• 第二种是通过super去调用

  super(Student, self).__init__(sex)

但是这种情况必须继承object(子类继承object就行)否则会报错

super(Student, self).init(sex)
TypeError: super() argument 1 must be type, not classobj

这里的区别就是经典类和新式类，其看下边的栗子：

class A:  
    def foo(self):  
        print('called A.foo()')  
  
  
class B(A):  
    pass  
  
  
class C(A):  
    def foo(self):  
        print('called C.foo()')  
  
  
class D(B, C):  
    pass  
  
  
if __name__ == '__main__':  
    d = D()  
    d.foo()

运行：called A.foo()

class A:  
    def foo(self):  
        print('called A.foo()')  
  
  
class B(A):  
    pass  
  
  
class C(A):  
    def foo(self):  
        print('called C.foo()')  
  
  
class D(B, C,object):  
    pass  
  
  
if __name__ == '__main__':  
    d = D()  
    d.foo()

运行：

called C.foo()

可见在调用父类方法查找的时候顺不一样。经典类会从根部开始，新式类从最接近子类的位置开始匹配。