一、概述

　　反射我们以后会经常用到，这个东西实现了动态的装配，通过字符串来反射类中的属性和方法

二、反射函数

2.1 hasarttr(obj,name_str)

作用：判断一个对象obj中是否有对应的name_str字符串的属性或者方法

class Dog(object): def __init__(self,name): self.name = name def eat(self,food): print("{0} is eating...{1}".format(self.name,food)) d = Dog("shabi") choice = input(">>>:").strip() print(hasattr(d,choice)) #obj中是否有对应的choice字符串的属性或者方法 #输出 >>>:name #输入对象存在属性 True >>>:eat #输入对象存在的方法 True

2.2 getattr(obj,name_str)

作用：根据字符串name_str获取obj对象中的对应方法的内存地址或者对应属性的值

 

class Dog(object): def __init__(self,name): self.name = name def eat(self,food): print("{0} is eating...{1}".format(self.name,food)) d = Dog("shabi") choice = input(">>>:").strip() print(getattr(d,choice)) #choice获取obj对象中的对应方法的内存地址或者对应属性的值 #输出 >>>:name #返回name属性的值 shabi >>>:eat <bound method Dog.eat of <__main__.Dog object at 0x00000157A129CF28>> #返回eat方法的内存地址

2.3 setattr(x,y,z)

作用：给obj对象添加一个新属性或者新方法，setattr(x, 'y', v) is equivalent to ``x.y = v''

①给对象新增一个新方法

 

def bulk(self): #先定义一个bulk函数 print("{0} is yelling...".format(self.name)) class Dog(object): def __init__(self,name): self.name = name def eat(self,food): print("{0} is eating...{1}".format(self.name,food)) d = Dog("shabi") choice = input(">>>:").strip() setattr(d,choice,bulk) #输入的是talk，所以又等同于d.talk = bulk #d.talk(d) 直接写死，用d.talk(d),一般不这么写 func = getattr(d,choice) #用getattr来获取 func(d) #输出 >>>:talk shabi is yelling...

 

 ②给对象新增一个属性

class Dog(object): def __init__(self,name): self.name = name def eat(self,food): print("{0} is eating...{1}".format(self.name,food)) d = Dog("shabi") choice = input(">>>:").strip() setattr(d,choice,22) #输入的是age，所以又等同于d.age = 22 # print(d.age) 这样就写死了，还是用下面一种 print(getattr(d,choice)) #输出 >>>:age 22

2.4  delattr(x,y)

 作用：删除obj对象中的属性或者方法，delattr(x, 'y') is equivalent to ``del x.y''

 

class Dog(object): def __init__(self,name): self.name = name def eat(self,food): print("{0} is eating...{1}".format(self.name,food)) d = Dog("shabi") choice = input(">>>:").strip() delattr(d,choice) #根据字符串删除属性或者方法 print(d.name) print(d.eat) #输出 >>>:name #删除属性name Traceback (most recent call last): File "E:/PycharmProjects/pythontest/day7/反射/反射.py", line 22, in <module> print(d.name) AttributeError: 'Dog' object has no attribute 'name' >>>:eat #删除方法eat Traceback (most recent call last): File "E:/PycharmProjects/pythontest/day7/反射/反射.py", line 21, in <module> delattr(d,choice) AttributeError: eat

三、综合使用

3.1 综合使用hasattr、getattr、setatt

class Dog(object): def __init__(self,name): self.name = name def eat(self,food): print("{0} is eating...{1}".format(self.name,food)) d = Dog("shabi") choice = input(">>>:").strip() if hasattr(d,choice): #判断d对象中存在属性和方法 name_value = getattr(d,choice) #获取属性值 print(name_value) setattr(d,choice,"hong") #修改属性值 print(getattr(d,choice)) #重新获取属性的值 else: setattr(d,choice,None) #设置不存在的属性值为None v = getattr(d,choice) print(v) #输出 >>>:name shabi hong >>>:abc None

 

转载于:https://www.cnblogs.com/xiangjun555/articles/7000024.html