python class
分为三个部分：class and object(类与对象),inheritance(继承),overload(重载)and override(覆写)。
class and object
类的定义，实例化。及成员訪问。顺便提一下python中类均继承于一个叫object的类。
class Song(object):#definition
def __init__(self, lyrics):
self.lyrics = lyrics#add attribution
def sing_me_a_song(self):#methods
for line in self.lyrics:
print line
happy_bday = Song(["Happy birthday to you",
"I don't want to get sued",
"So I'll stop right there"])#object1
bulls_on_parade = Song(["They rally around the family",
"With pockets full of shells"])#object2
happy_bday.sing_me_a_song()#call function
bulls_on_parade.sing_me_a_song()inheritance(继承)
python支持继承。与多继承。可是一般不建议用多继承。由于不安全哦！
class Parent(object):
def implicit(self):
print "PARENT implicit()"
class Child(Parent):
pass
dad = Parent()
son = Child()
dad.implicit()
son.implicit()overload(重载)and override(覆写)
重载（overload）和覆盖（override）。在C++，Java。C#等静态类型语言类型语言中，这两个概念同一时候存在。
python尽管是动态类型语言，但也支持重载和覆盖。
可是与C++不同的是，python通过參数默认值来实现函数重载的重要方法。
以下将先介绍一个C++中的重载样例，再给出相应的python实现，能够体会一下。
C++函数重载样例：
void f(string str)//输出字符串str 1次
{
cout<<str<<endl;
}
void f(string str,int times)//输出字符串 times次
{
for(int i=0;i<times;i++)
{
cout<<str<<endl;
}
}python实现：
通过參数默认值实现重载
<span style="font-size:18px;">def f(str,times=1):
print str*times
f('sssss')
f('sssss',10)</span>覆写
class Parent(object):
def override(self):
print "PARENT override()"
class Child(Parent):
def override(self):
print "CHILD override()"
dad = Parent()
son = Child()
dad.override()
son.override()super()函数
函数被覆写后。怎样调用父类的函数呢？
class Parent(object):
def altered(self):
print "PARENT altered()"
class Child(Parent):
def altered(self):
print "CHILD, BEFORE PARENT altered()"
super(Child, self).altered()
print "CHILD, AFTER PARENT altered()"
dad = Parent()
son = Child()
dad.altered()
son.altered()python中。子类自己主动调用父类_init_()函数吗？
答案是否定的，子类须要通过super()函数调用父类的_init_()函数
class Child(Parent):
def __init__(self, stuff):
self.stuff = stuff
super(Child, self).__init__()