python-装饰器,类与对象,私有字段,析构,__call__,继承,多继承,接口

Posted 2020-09-17

1、装饰器执行流程

装饰器：将原函数替换为wrapper函数

def outer()

@outer  --- func1作为参数传入outer()

def wrapper()  --- wrapper()放入内存

return wrapper   --- 返回wrapper地址，Func1重新赋值为wrapper

Func1()  --- 调用func1函数

def wrapper()

print ‘验证‘

def Func1()

print ‘func1‘

[[email protected] decorate]# python main.py
验证
func1
验证
func2
[[email protected] decorate]# cat main.py
#!/usr/bin/python27
#coding:utf-8

def outer(fun):
    def wrapper():
        print ‘验证‘
        fun()
    return wrapper

@outer
def Func1():
    print ‘func1‘

@outer
def Func2():
    print ‘func2‘

‘‘‘
Func1=
def wrapper():
    print ‘验证‘
    fun()
‘‘‘

Func1()
Func2()
[[email protected] decorate]#

带参数的装饰器

[[email protected] decorate]# python27 main1.py
验证
func1 alex
[[email protected] decorate]# cat main1.py
#!/usr/bin/python27
#coding:utf-8

def outer(fun):
    def wrapper(arg):
        print ‘验证‘
        fun(arg)
    return wrapper

@outer
def Func1(arg):
    print ‘func1‘,arg

‘‘‘
Func1=
def wrapper(arg):
    print ‘验证‘
    fun(arg)
‘‘‘

Func1(‘alex‘)
[[email protected] decorate]#

在函数执行的前后，执行任意函数

def Filter(before_func,after_func): 

    def outer(main_func):

         def wrapper(request,kargs): 

            before_result = before_func(request,kargs)

            if(before_result != None): 

                return before_result;

  
            main_result = main_func(request,kargs)

            if(main_result != None):

                return main_result;

  
            after_result = after_func(request,kargs)

            if(after_result != None):

                 return after_result;

         return wrapper

     return outer 

@Filter(AccountFilter.Before, AccountFilter.After) def List(request,kargs):

  pass

2、类与对象

封装性：将name,age属性封装到self中

[[email protected] ~]# python27 index.py
cxiong 29
xmzhang 28
中国

[[email protected] ~]# cat index.py
#!/usr/bin/python27
#coding:utf-8

class Person():
    nation=‘中国‘    --- 静态字段：nation属于class
    def __init__(self,name,age):
        self.name=name  --- 动态字段：self.name属于对象
        self.age=age    ---动态字段：self.age属于对象

p1=Person(‘cxiong‘,29)
p2=Person(‘xmzhang‘,28)

print p1.name,p1.age
print p2.name,p2.age

print p1.nation
[[email protected] ~]#

注意：类不能访问动态字段；对象可以访问静态字段

静态字段、动态字段、静态方法、动态方法和装饰器

作用：提供统一的方法和数据，用于处理类的请求

[[email protected] ~]# cat index.py
#!/usr/bin/python27
#coding:utf-8

class Person():
   
    #静态字段
    nation=‘中国‘

    def __init__(self,name,age):
        #动态字段
        self.name=name
        self.age=age

    #动态方法   
    def Eat(self):
        print self.name+‘ eating...‘

    #静态方法  --- 不需要实例化类，即可调用方法
    @staticmethod
    def Breath():
        print ‘breathing...‘
   
    #装饰器 --- 将方法访问形式作为字段形式访问
    @property
    def Sing(self):
        print self.name+‘ singing...‘

p1=Person(‘cxiong‘,29)
p2=Person(‘xmzhang‘,28)

print p1.name,p1.age
print p2.name,p2.age
print p1.nation
p1.Eat()
p2.Eat()
Person.Breath()   
p1.Sing

3、面向对象与函数式编程的区别

静态方法与模块形式的区别：内存上没区别，区别在于，静态方法逻辑上属于类；

静态方法是面向对象语言解决对象重复构造方法时产生的，python模块化语言也可以解决；

多态：将相似的方法包装在同一个模块中；

python支持模块化编程，也支持反射；等同于面向对象编程java、.net

面向对象：可以创建模板

4、私有字段和私有方法

作用：安全

[[email protected] ~]# python index1.py
male
[[email protected] ~]# cat index1.py
#!/usr/bin/python27
#coding:utf-8

class Person():
   
    #静态字段
    nation=‘中国‘

    def __init__(self,name,age,gender):
        #动态字段
        self.name=name
        self.age=age
        #私有字段
        self.__gender=gender

    #动态方法   
    def Eat(self):
        print self.name+‘ eating...‘

    #静态方法
    @staticmethod
    def Breath():
        print ‘breathing...‘
   
    #装饰器
    @property
    def Sing(self):
        print self.name+‘ singing...‘

    @property --- 私有字段不能被外部访问，但是可以使用方法访问
    def ShowGender(self):
        return self.__gender

p1=Person(‘cxiong‘,29,‘male‘)
p2=Person(‘xmzhang‘,28,‘female‘)
print p1.ShowGender

只读私有字段和可改写私有字段

[[email protected] ~]# cat index1.py
#!/usr/bin/python27
#coding:utf-8

class Person():   --- 没有继承object是可读可写；继承了object一个是可读，一个是可写
    
    #静态字段
    nation=‘中国‘

    def __init__(self,name,age,gender):   --- 构造函数
        #动态字段
        self.name=name
        self.age=age
        #私有字段
        self.__gender=gender

    #动态方法   
    def Eat(self):
        print self.name+‘ eating...‘

    #静态方法
    @staticmethod
    def Breath():
        print ‘breathing...‘
   
    #装饰器
    @property
    def Sing(self):
        print self.name+‘ singing...‘
   
    #只读私有字段
    @property
    def ShowGender(self):
        return self.__gender

    #可改私有字段
    @ShowGender.setter
    def ShowGender(self,value):
        self.__gender=value

p1=Person(‘cxiong‘,29,‘male‘)
p2=Person(‘xmzhang‘,28,‘female‘)
print p1.ShowGender
p1.ShowGender=‘female‘
print p1.ShowGender

5、析构函数及__call__方法

[[email protected] ~]# python index1.py
male
female
解释器要销毁person了...
解释器要销毁person了...
[[email protected] ~]# cat index1.py
#!/usr/bin/python27
#coding:utf-8

class Person(object):
   
    #静态字段
    nation=‘中国‘

    #构造函数
    def __init__(self,name,age,gender):
        #动态字段
        self.name=name
        self.age=age
        #私有字段
        self.__gender=gender
   
    #析构函数，用于销毁对象时使用；一般不使用，常用于操作文件
    def __del__(self):
        print ‘解释器要销毁person了...‘

    def __call__(self):
        print ‘call‘

    #动态方法   
    def Eat(self):
        print self.name+‘ eating...‘

    #静态方法
    @staticmethod
    def Breath():
        print ‘breathing...‘
   
    #装饰器
    @property
    def Sing(self):
        print self.name+‘ singing...‘
   
    #只读私有字段
    @property
    def ShowGender(self):
        return self.__gender

    #可改私有字段
    @ShowGender.setter
    def ShowGender(self,value):
        self.__gender=value

p1=Person(‘cxiong‘,29,‘male‘)
p2=Person(‘xmzhang‘,28,‘female‘)
print p1.ShowGender
p1.ShowGender=‘female‘
print p1.ShowGender

p1()  #执行__call__方法

[[email protected] ~]# python index1.py
male
female
call
解释器要销毁person了...
解释器要销毁person了...

6、继承

[[email protected] ~]# python index1.py
work hard...
cxiong singing...
breathing...
解释器要销毁person了...
[[email protected] ~]# cat index1.py
#!/usr/bin/python27
#coding:utf-8

class Person(object):
   
    #静态字段
    nation=‘中国‘

    #构造函数
    def __init__(self,name,age,gender):
        #动态字段
        self.name=name
        self.age=age
        #私有字段
        self.__gender=gender
   
    #析构函数
    def __del__(self):
        print ‘解释器要销毁person了...‘

    #动态方法   
    def Eat(self):
        print self.name+‘ eating...‘

    #
    def __call__(self):
        print ‘call‘

    #静态方法
    @staticmethod
    def Breath():
        print ‘breathing...‘
   
    #装饰器
    @property
    def Sing(self):
        print self.name+‘ singing...‘
   
    #只读私有字段
    @property
    def ShowGender(self):
        return self.__gender

    #可改私有字段
    @ShowGender.setter
    def ShowGender(self,value):
        self.__gender=value

#man继承Person类，私有方法__gender无法继承
class man(Person):

    #重写__init__方法
    def __init__(self):
        self.name=‘cxiong‘
        self.__gender=‘male‘

    #新增work方法
    def work(self):
        print ‘work hard...‘

m1=man()
m1.work()
m1.Sing
m1.Breath()

7、新式类与经典类的区别

新式类：继承object

经典类：不继承object

使用新式类的原因：经典类存在多继承bug，深度优先，而非广度优先，请参考以下内容

https://docs.python.org/release/2.2.3/whatsnew/sect-rellinks.html

[[email protected] ~]# cat index1.py
#!/usr/bin/python27
#coding:utf-8

class Person(object):
   
    #静态字段
    nation=‘中国‘

    #构造函数
    def __init__(self,name,age,gender):
        #动态字段
        self.name=name
        self.age=age
        #私有字段
        self.__gender=gender
        print ‘person init...‘
   
    #析构函数
    def __del__(self):
        print ‘解释器要销毁person了...‘

    #动态方法   
    def Eat(self):
        print self.name+‘ eating...‘

    #
    def __call__(self):
        print ‘call‘

    #静态方法
    @staticmethod
    def Breath():
        print ‘breathing...‘
   
    #装饰器
    @property
    def Sing(self):
        print self.name+‘ singing...‘
   
    #只读私有字段
    @property
    def ShowGender(self):
        return self.__gender

    #可改私有字段
    @ShowGender.setter
    def ShowGender(self,value):
        self.__gender=value

#man继承Person类   
class man(Person):

    #重写__init__方法
    def __init__(self):
        self.name=‘cxiong‘
        self.__gender=‘male‘
        print ‘man init...‘
        #调用父类的init方法1
        Person.__init__(self,‘cxiong‘,29,‘male‘)
        #调用父类的init方法2
        super(man,self).__init__(‘cxiong‘,29,‘male‘)

    #新增work方法
    def work(self):
        print ‘work hard...‘

m1=man()
m1.work()
m1.Sing
m1.Breath()

[[email protected] ~]# python index1.py
man init...
person init...
person init...
work hard...
cxiong singing...
breathing...
解释器要销毁person了...
[[email protected] ~]#

8、多继承

python特有的特性

[[email protected] ~]# python multiple.py
this is D
save method from --A--
[[email protected] ~]# cat multiple.py
#!/usr/bin/python27
#coding:utf-8

class A:
    def __init__(self):
        print ‘this is A‘
    def save(self):
        print ‘save method from --A--‘

class B(A):
    def __init__(self):
        print ‘this is B‘

class C(A):
    def __init__(self):
        print ‘this is C‘
    def save(self):
        print ‘save method from --C--‘

class D(B,C):
    def __init__(self):
        print ‘this is D‘

c=D()
c.save()
[[email protected] ~]# vim multiple.py
[[email protected] ~]# python multiple.py
this is D
save method from --C--
[[email protected] ~]# cat multiple.py
#!/usr/bin/python27
#coding:utf-8

class A(object):
    def __init__(self):
        print ‘this is A‘
    def save(self):
        print ‘save method from --A--‘

class B(A):
    def __init__(self):
        print ‘this is B‘

class C(A):
    def __init__(self):
        print ‘this is C‘
    def save(self):
        print ‘save method from --C--‘

class D(B,C):
    def __init__(self):
        print ‘this is D‘

c=D()
c.save()
[[email protected] ~]#

9、接口

规范：抽象类+抽象方法=接口

from abc import ABCMeta, abstractmethod

class Bar:

     __metaclass__ = ABCMeta 
    @abstractmethod    

    def Fun(self):pass

  

class Foo(Bar):    

    def __init__(self):

         print ‘__init__‘

 
Foo()