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 = '123'
    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('	',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