python基础七

subprocess

subprocess是专门用来替代os.system;os.spawn更加的先进。

但是subprocess.run()是在python3.5之后才出现的

实例

>>> subprocess.run(["df",'-h'])

以上代码运行结果

Filesystem Size Used Avail Use% Mounted on
/dev/vda3 91G 2.3G 84G 3% /
tmpfs 3.9G 0 3.9G 0% /dev/shm
/dev/vda1 194M 65M 120M 35% /boot
CompletedProcess(args=['df', '-h'], returncode=0)

接收字符串格式命令，返回元组形式，第1个元素是执行状态，第2个是命令结果

实例一

>>> subprocess.getstatusoutput("ls /application/tools")

以上代码运行结果

(0, 'Python-3.5.2\nPython-3.5.2.tgz')

实例二

>>> print((subprocess.getstatusoutput("ls /application/tools/")[1]))

以上代码运行结果

Python-3.5.2
Python-3.5.2.tgz

subprocess.Popen既可以打印正确输出stdout，也可以打印错误输出stderr。

>>> res=subprocess.Popen("ifconfig|grep 10.0",shell=True,stdout=subprocess.PIPE,stderr=subprocess.PIPE)
>>> res.stdout.read()

以上代码运行结果

>>> res.stdout.read()
b'          inet addr:10.0.1.14  Bcast:10.0.1.255  Mask:255.255.255.0\n          collisions:0 txqueuelen:1000 \n          collisions:0 txqueuelen:1000 \n'

对于要等待的命令

>>> res=subprocess.Popen("sleep 10;echo 'hello'",shell=True,stdout=subprocess.PIPE,stderr=subprocess.PIPE)

当上面的命令执行完了之后， res.poll()的执行结果为0，res.wait()的执行结果为0，res.terminate()用来中断正在执行的命令。

面向对象

面向对象 object oriented programing

类的特性

封装

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

继承

通过父类-》子类的方式以最小代码量的方式实现 不同角色的共同点和不同点的同时存在

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

class Dog(object):

    def __init__(self,name):
        self.name=name

    def sayhi(self):
        print("hello ,I am a dog. My name is %s"%self.name)

# Dog().sayhi()
d=Dog("wangcai")
d.sayhi()

以上代码运行结果

hello ,I am a dog. My name is wangcai

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

class Role(object):
    def __init__(self, name, role, weapon, life_value=100, money=15000):
        self.name = name
        self.role = role
        self.weapon = weapon
        self.life_value = life_value
        self.money = money
        self.__heart = "Normal"
    def status(self):
        print("%s is %s and have %s"%(self.name,self.role,self.weapon))

    def shot(self):
        print("%s is shooting..." % self.name)

    def got_shot(self):
        print("ah...,I got shot...")
        self.__heart ="Die"

        print(self.__heart)
    def get_heart(self):
        return self.__heart

    def buy_gun(self, gun_name):
        print("%s just bought %s" % (self.name,gun_name) )
        self.weapon = gun_name

r1 = Role('HaiTao', 'police', 'AK47') #生成一个角色
r2 = Role('Jack', 'terrorist','B22')  #生成一个角色
print(r1.name)
print(r1.get_heart())
r1.got_shot()

print(r1._Role__heart)  #强制访问私有属性

以上代码运行结果

HaiTao
Normal
ah...,I got shot...
Die
Die

公有属性

nationality = "JP" 在类里直接定义的属性即是公有属性

class Role(object):

    nationality  = "JP"

    def __init__(self, name, role, weapon, life_value=100, money=15000):
        self.name = name
        self.role = role
        self.weapon = weapon
        self.life_value = life_value
        self.money = money
        self.__heart = "Normal"

    def shot(self):
        print("%s is shooting..." % self.name)

    def got_shot(self):
        print("ah...,I got shot...")
        self.__heart ="Die"

    # def __del__(self):
    #     print("del.....run...")

r1 = Role("HaiTao", "警察","B22")
r2 = Role("LiChuang", "警犬","B13")
print(r1.nationality)
print(r2.nationality)
Role.nationality = "US" #更改类的公有属性
print(r1.nationality,r2.nationality)
r1.nationality = "CN"
print("after change...")
print(r1.nationality)
print(r2.nationality)

以上代码运行结果

JP
JP
US US
after change...
CN
US

私有函数

class Role(object):

    nationality  = "JP"

    def __init__(self, name, role, weapon, life_value=100, money=15000):
        self.name = name
        self.role = role
        self.weapon = weapon
        self.life_value = life_value
        self.money = money
        self.__heart = "Normal"

    def shot(self):
        print("%s is shooting..." % self.name)

    def got_shot(self):
        print("ah...,I got shot...")
        self.__heart ="Die"

    # def __del__(self):
    #     print("del.....run...")

r1 = Role("HaiTao", "警察","B22")
r2 = Role("LiChuang", "警犬","B13")
def shot2(self):
    print("run my own shot method", self.name )
r1.shot = shot2
r1.shot(r1)
r2.shot()

以上代码运行结果

run my own shot method HaiTao
LiChuang is shooting...

析构方法__del__

用于在实例被python的回收机制销毁时关闭实例打开的临时文件

class Role(object):

    nationality  = "JP"

    def __init__(self, name, role, weapon, life_value=100, money=15000):
        self.name = name
        self.role = role
        self.weapon = weapon
        self.life_value = life_value
        self.money = money
        self.__heart = "Normal"

    def shot(self):
        print("%s is shooting..." % self.name)

    def got_shot(self):
        print("ah...,I got shot...")
        self.__heart ="Die"

    def __del__(self):
        print("del.....run...")

r1 = Role("HaiTao", "警察","B22")

以上代码运行结果

del.....run...

继承

子类有就用子类，子类没有继承父类

class Person(object):
    def talk(self):
        print("person is talking...")

class BlackPerson(Person):
    def talk(self):
        print("black person is blaba....")
    def walk(self):
        print("is walking")
b=BlackPerson()
b.talk()
b.walk()

以上代码执行结果

black person is blaba....
is walking

先继承，再重构

class Person(object):

    def __init__(self,name,age):
        self.name=name
        self.age=age
        self.sex="normal"

    def talk(self):
        print("person is talking...")

class WhitePerson(Person):
    pass

class BlackPerson(Person):
    def __init__(self,name,age,strength): #先覆盖
        Person.__init__(self,name,age)　　#再继承
        self.strength=strength　　　　　　 #再添加自己的东西
        print(self.name,self.age,self.sex,self.strength)

    def talk(self):
        print("black person is blaba....")
    def walk(self):
        print("is walking")
b=BlackPerson(","strong")

class Person(object):

    def __init__(self,name,age):
        self.name=name
        self.age=age
        self.sex="normal"

    def talk(self):
        print("person is talking...")

class WhitePerson(Person):
    pass

class BlackPerson(Person):
    def __init__(self,name,age,strength): #先覆盖
        super(BlackPerson,self).__init__(name,age)#再继承(新式类)
        #Person.__init__(self,name,age)　　#再继承（旧式类）
        self.strength=strength　　　　　　 #再添加自己的东西
        print(self.name,self.age,self.sex,self.strength)

    def talk(self):
        print("black person is blaba....")
    def walk(self):
        print("is walking")
b=BlackPerson(","strong")

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 enrolled a new school member [%s]"% self.name)
        SchoolMember.member +=1

    def tell(self):
        print("------info:%s-----"%self.name)
        for k,v in self.__dict__.items():
            print("\t",k,v)

        print("------end-----")

    def __del__(self):
        print("开除了[%s]..."% self.name )
        SchoolMember.member -=1

class School(object):
     '''学校类'''
     def open_branch(self,addr):
         print("openning a new branch in ",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
    # def tell(self):
    #     print("""--------info:%s
    #         name:%s
    #         age:%s
    #         salary :%s
    #     """ % (self.name,self.name,self.age,self.salary))
    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 #fee
        self.amount = 0
    def pay_tuition(self,amount):
        print("student [%s] has just paied [%s]" %(self.name,amount))
        self.amount += amount

t1 = Teacher("Wusir", 28, "F*M",3000,"Python" )
s1 = Student("HaiTao", 38,"N/A","PYS15", 300000 )
s2 = Student("LIChuang",12,"M","PYS15", 11000 )

print(SchoolMember.member)
t1.tell()
t1.open_branch("SH")
s2.tell()
del s2

print(SchoolMember.member)

以上代码运行结果

just enrolled a new school member [Wusir]
just enrolled a new school member [HaiTao]
just enrolled a new school member [LIChuang]
3
------info:Wusir-----
     sex F*M
     age 28
     name Wusir
     salary 3000
     course Python
------end-----
openning a new branch in  SH
------info:LIChuang-----
     sex M
     amount 0
     age 12
     name LIChuang
     tuition 11000
     course PYS15
------end-----
开除了[LIChuang]...
2
开除了[Wusir]...
开除了[HaiTao]...

经典类VS新式类

class A(object):
    # pass

    def __init__(self):
        self.n = "A"
class B(A):
    # pass
    def __init__(self):
        self.n = "B"
class C(A):
    # pass
    def __init__(self):
        self.n = "C"
class D(B,C):
    pass
    # def __init__(self):
    #     self.n = "D"
d = D()
print(d.n)

以上代码运行结果

B

多态

允许将子类类型的指针赋值给父类类型的指针。

class Animal:
    def __init__(self, name):    # Constructor of the class
        self.name = name

    def talk(self):              # Abstract method, defined by convention only
        raise NotImplementedError("Subclass must implement abstract method")

class Cat(Animal):
    def talk(self):
        return 'Meow!'
class Dog(Animal):
    def talk(self):
        return 'Woof! Woof!'
d = Dog("d1")
c = Cat("C1")
# Animal.talk(d)
# Animal.talk(c)
def animal_talk(obj):
    print(obj.talk())
animal_talk(d)
animal_talk(c)

以上代码运行结果

Woof! Woof!
Meow!