1.创建一个类

class Employee:    empCount = 0    def __init__(self,name,salary):        self.name = name        self.salary = salary        Employee.empCount +=1    def displayEmployee(self):        print "Name：",self.name,",Salary:",self.salary#创建Employee类的一个对象emp1 = Employee("Zara",2000)emp2 = Employee("Manni",5000)emp1.displayEmployee()emp2.displayEmployee()print "Total Employee %d" % Employee.empCount

2.修改与删除属性

注：使用del a以后，它就像变量a从来没有存在过一样

class Employee:    empCount = 0    def __init__(self,name,salary):        self.name = name        self.salary = salary        Employee.empCount +=1    def displayEmployee(self):        print "Name??",self.name,",Salary:",self.salaryemp1 = Employee("Zara",2000)emp2 = Employee("Manni",5000)#修改属性emp1.salary = "aa"emp1.displayEmployee() #删除属性#del emp2.salary;

3.Python对象销毁(垃圾回收)

Python使用了引用计数来追踪内存中的对象

一个内部跟踪对象，称为一个引用计数器

当对象被创建时，就创建了一个引用计数，当这个对象不再需要时，也就是说，这个对象的引用计数变为0时，它被垃圾回收。但是回收不是“立即”的，由解释器在适当的时机，将垃圾对象占用的内存空间回收

Python的垃圾收集器实际上是一个引用计数器和一个循环垃圾收集器

__del__是析构函数

class Point:    def __init__(self,x=0,y=0):        self.x = x        self.y = y

def __del__(self):        class_name = self.__class__.__name__        print class_name,"销毁"pt1 = Point()pt2 = pt1pt3 = pt2print id(pt1),id(pt2),id(pt3)del pt1del pt2del pt3

4.类的继承

class Parent:    parentAttr = 100    def __init__(self):        print "调用父类构造函数"    def parentMethod(self):        print "调用父类方法"    def setAttr(self,attr):        Parent.parentAttr = attr    def getAttr(self):        print "父类属性：",Parent.parentAttrclass Child(Parent):    def __init__(self):        print "调用子类构造方法"    def childMethod(self):        print "调用子类方法"child = Child()#调用子类构造方法child.childMethod()#调用子类方法child.parentMethod()#调用父类方法child.setAttr(200)child.getAttr()#父类属性： 200

例子2

#-*_coding:utf-8-*-class SchoolMember:    def __init__(self,name,age):        self.name = name        self.age = age        print 'Initialized SchoolMember:%s'%self.name    def tell(self):        print "'Name:%s' Age:%s"%(self.name,self.age)class Teacher(SchoolMember):    def __init__(self,name,age,salary):        SchoolMember.__init__(self,name,age)        self.salary = salary#写了这句salary才会成为Teacher的属性        print 'Salary:%d'%self.salaryclass Student(SchoolMember):    def __init__(self,name,age,marks):        SchoolMember.__init__(self,name,age)        self.marks = marks        print 'Marks :%d'%self.markst = Teacher('Mrs.Lee',23,5000)s = Student('Jin',24,98)

5.类的多继承

class A:    passclass B:    passclass C(A,B):    pass

6.调用子类方法

class Parent:    def myMethod(self):        print "调用父类方法"    class Child(Parent):    def myMethod(self):        print "调用子类方法"child = Child()child.myMethod()#调用子类方法

7.运算符重载

class Vector:    def __init__(self,a,b):        self.a = a        self.b = b    def __add__(self,other):        return Vector(self.a + other.a,self.b + other.b)    def __str__(self):        return "Vector(%d,%d)" %(self.a,self.b)v1 = Vector(2,10)v2 = Vector(5,-2)print v1+v2#Vector(7,8)

8.声明类的私有成员

类的私有属性：__private_attrs：两个下划线开头，声明该属性为私有，不能在类的外部被使用，在类的内部使用self.__private_attrs

类的室友方法：__private_method：两个下划线开头，声明该方法为私有方法，不能在类的外部调用，在类的内部使用self__private_method

class JustCounter:    __secreCount =0    publicCount =0    def count(self):        self.__secreCount+=1        self.publicCount+=1        print self.__secreCountcounter = JustCounter()counter.count()counter.count()print counter.publicCountprint counter.__secreCount#报错,私有