Python之路，day7-Python基础

os.system 输出命令结果到屏幕，返回命令执行状态
os.popen（"dir"）.read()#会保存命令的执行结果输出

py2.7
commands
commands.getstatusoutput("dir")
#windows不好用
#linux可以

subprocess
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面向对象

模板造对象

一.类的特性

1.封装
    防止数据被随意修改
    使外部程序不需要关注对象内部的构造（逻辑结构)，只需要通过此对象对外提供的接口进行直接访问即可

 class Dog(object):

     def __init__(self,name,food):#构造函数，构造方法，==初始化方法
         self.NAME = name
         self.FOOD = food
         self.__getj = 'big'
         self.__test = ''
     def sayhi(self):#类的方法（类的具体方法）
         print("hello,ni shuo de dui.",self.NAME)
     def get_getj(self):
         return self.__getj
     def eat(self):
         print("%s is eating %s"%(self.NAME,self.FOOD))
     def __del__(self):
         print("del...run....")

 d = Dog("a1",'haochide')#Dog(d,"a1") #实例化后产生的对象叫实例（当前类的实例）
 d2 = Dog("a2",'pi')

 d.sayhi()
 d2.sayhi()
 d.eat()
 d2.eat()
 print(d.get_getj())

 print(d._Dog__test)

 def shot2():
     print("buhuia")

 d.sayhi = shot2
 d.sayhi()
 # print(d.test)

2.继承
    通过父类---》子类的方式 实现不同角色的共同点和不同点 以最小代码量的方式实现

类 ----》实例化----》实例对象

__init__构造函数

self.name = name #属性，成员变量，字段

def sayhi（） #方法，动态属性

公有属性
    在类里定义的属性，任何对象都可以访问

私有属性
    __private_attr_name = value

    def get_heart(self) #对外部提供只读访问接口
        return self.__heart

    r1._Role__heart 强制访问私有属性

析构方法

继承

多继承

 class Person(object):
     def __init__(self,name,age):
         self.name = name
         self.age = age
         self.sex = 'male'

     def talk(self):
         print("person is talk",self.name)

 class BlackPerson(Person):
     def __init__(self,name,age):
         Person.__init__(self,name,age)
         print(self.sex)

     def walk(self):
         print("is walk")

 b = BlackPerson('liusijia',10)
 b.talk()

新式类vs经典类
    SchoolMember.__init__(self,name,age,sex)   #经典类写法
        super(Teacher,self).__init__(name,age,sex)#新式类写法

class Person(object):
    super(Person)

class Person:#经典类
    ParentClass.__init__

 class SchoolMember(object):
     '''学校成员基类'''
     member = 0
     def __init__(self,name,age,sex):
         self.name = name
         self.age = age
         self.sex = sex
         self.enroll()
     def enroll(self):
         '''注册'''
         print("just encolled a new school member %s"%self.name)
         SchoolMember.member +=1

     def tell(self):
         '''个人信息'''
         print('------info:%s-----'%self.name)
         for k,v in self.__dict__.items():
             print('\t',k,v)
     def __del__(self):
         print("开除[%s]..."%self.name)
         SchoolMember.member -=1

 class School(object):
     '''学校类'''
     def open_branch(self,addr):
         print("openning branch in %s"%addr)
         self.addr = ""

 class Teacher(SchoolMember,School):
     '''讲师类'''
     def __init__(self,name,age,sex,salary,course):
         SchoolMember.__init__(self,name,age,sex)   #经典类写法
         super(Teacher,self).__init__(name,age,sex)#新式类写法

         self.salary = salary
         self.course = course
         # self.enroll()

     def teaching(self):
         print("Teacher[%s]is teaching[%s]"%(self.name,self.course))

 class Student(SchoolMember):
     def __init__(self,name,age,sex,course,tuition):
         SchoolMember.__init__(self,name,age,sex)
         self.course = course
         self.tuition = tuition
         self.amount = 0

     def pay_tuition(self,amount):
         print("student[%s]has just paied [%s]"%(self.name,amount))
         self.amount += amount

 t1 = Teacher("a1",11,"F*M",3000,"python")
 s1 = Student("a2",14,"NA","py",3000)
 s2 = Student("a3",13,"NA","py",3000)

 print(SchoolMember.member)

 del s1
 print(SchoolMember.member)

 t1.tell()
 s2.tell()

3.多态

静态方法

类方法

属性方法