本节内容
- 概述
- 反射函数
- 综合使用
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
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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
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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
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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>>>:talkshabi is yelling... |
②给对象新增一个属性
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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>>>:age22 |
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''
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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nameTraceback (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eatTraceback (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、setattr
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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>>>:nameshabihong>>>:abcNone |