概述
反射实现动态装配，通过字符串来反射类中的属性和方法
反射函数
1、hasattr(obj,name_str) 作用：判断一个对象obj是否存在name_str的属性或者方法
1 class Dog(object): 2 def __init__(self, name): 3 self.name = name 4 5 def eat(self): 6 print("%s eating...."% self.name) 7 d = Dog("JJ") 8 choice = input(">>>").strip() 9 print(hasattr(d, choice)) 10 11 结果： 12 >>>ss 13 False 14 15 或者 16 17 >>>eat 18 True
2、getattr(obj, name_str) 作用：根据字符串name_str获取obj对象中的内存地址或者对应的属性值
class Dog(object): def __init__(self, name): self.name = name def eat(self): print("%s eating...."% self.name) d = Dog("JJ") choice = input(">>>").strip() if hasattr(d, choice): print(getattr(d,choice)) # 通过choice输入的字符串从d对象里寻找 结果： >>>eat <bound method Dog.eat of <__main__.Dog object at 0x0053C2F0>>
3、setattr(x,y,z) 作用：给obj添加一个新的属性或者方法
1）给对象新增一个方法
1 def bulk(self): 2 print("%s is yelling"% self.name) 3 4 5 class Dog(object): 6 def __init__(self, name): 7 self.name = name 8 9 def eat(self): 10 print("%s eating...."% self.name) 11 d = Dog("JJ") 12 choice = input(">>>").strip() 13 setattr(d, choice, bulk) 14 # d.talk(d) # 直接写死了，一般不用这种 15 func = getattr(d, choice) # 用getattr来获取 16 func(d) 17 18 结果： 19 >>>talk 20 JJ is yelling
2）给对象新增一个属性
1 class Dog(object): 2 def __init__(self, name): 3 self.name = name 4 5 def eat(self): 6 print("%s eating...."% self.name) 7 d = Dog("JJ") 8 choice = input(">>>").strip() 9 setattr(d, choice, 22) 10 # print(d.age) #直接写死了 一般不这么写 11 print(getattr(d, choice)) 12 13 结果： 14 >>>number 15 22
4、delattr(x, y) 作用：删除obj对象中的属性和方法，delattr(x, 'y') is equivalent to ``del x.y''
1 class Dog(object): 2 def __init__(self, name): 3 self.name = name 4 5 def eat(self): 6 print("%s eating...."% self.name) 7 d = Dog("JJ") 8 choice = input(">>>").strip() 9 delattr(d, choice) 10 print(d.eat) 11 print(d.name) 12 13 结果： 14 >>>eat 15 Traceback (most recent call last): 16 File "E:/python_3.5/stu/反射模块.py", line 14, in <module> 17 delattr(d, choice) 18 AttributeError: eat
1、hasattr
2、getattr
3、setattr
4、delattr
1)添加一个新方法
1 def bulk(self): 2 print("yelling......") 3 4 class Dog(object): 5 def __init__(self, name, age): 6 self.name = name 7 self.age = age 8 9 def eat(self, food): 10 print("%s eating....%s"%(self.name, food)) 11 12 d = Dog("Lidy", 2) 13 choice = input(">>>") 14 if hasattr(d, choice): 15 fun = getattr(d, choice) 16 fun("baozi") 17 else: 18 setattr(d, choice, bulk) 19 # print(getattr(d, choice)) 20 fun = getattr(d, choice) 21 fun(d) 22 23 24 结果： 25 >>>talk 26 yelling...... 27 28 或者 29 >>>eat 30 Lidy eating....baozi
2）添加新的属性
1 def bulk(self): 2 print("yelling......") 3 4 class Dog(object): 5 def __init__(self, name, age): 6 self.name = name 7 self.age = age 8 9 def eat(self, food): 10 print("%s eating....%s"%(self.name, food)) 11 12 d = Dog("Lidy", 2) 13 choice = input(">>>") 14 if hasattr(d, choice): 15 attr = getattr(d, choice) 16 else: 17 setattr(d, choice, 222) 18 19 print(getattr(d, choice)) 20 21 结果： 22 >>>name 23 Lidy 24 25 或者 26 >>>eee 27 222
3）删除属性
1 def bulk(self): 2 print("yelling......") 3 4 class Dog(object): 5 def __init__(self, name, age): 6 self.name = name 7 self.age = age 8 9 def eat(self, food): 10 print("%s eating....%s"%(self.name, food)) 11 12 d = Dog("Lidy", 2) 13 choice = input(">>>") 14 if hasattr(d, choice): 15 delattr(d, choice) 16 # attr = getattr(d, choice) 17 else: 18 setattr(d, choice, 222) 19 20 print(getattr(d, choice)) 21 # fun = getattr(d, choice) 22 # fun(d) 23 24 结果： 25 >>>name 26 Traceback (most recent call last): 27 File "E:/python_3.5/stu/类/反射.py", line 22, in <module> 28 print(getattr(d, choice)) 29 AttributeError: 'Dog' object has no attribute 'name'
