Use of getattr, hasattr, delattr and setattr in reflectors

Reflection

Mapping strings to instance variables or instance methods ,
Then you can call 、 Modify the operating
There are four important ways to reflect ：

• 1、getattr Get object properties / Method
• 2、hasattr Determine whether the object has corresponding attributes
• 3、delattr Delete the specified attribute
• 4、setattr Set content for object

getattr Get object properties / Method

class M211Vip:
    def welcome(self):
        print(" Congratulations on joining the organization !!!!!")

    def learning(self):
        print(" Is opening up the gap with others ......")

No use getattr Call before

M211Vip().mylearning()

Use getattr call mylearning（） Method , The difference is mylearning Is string

getattr(M211Vip(), "mylearning")()

setattr Set content for object

mylearning Is an external method of a class , stay M211Vip Cannot call , So you need to map the functions outside the class to the methods inside the class

class M211Vip:
    def welcome(self):
        print(" Congratulations on joining the organization !!!!!")

    def learning(self):
        print(" Is opening up the gap with others ......")


def mylearning():
    print(" In self-study ....")

Functions outside the class map to methods inside the class

bo = M211Vip()
 setattr(bo, "mylearning", mylearning) # Map first , Can be used getattr(bo, "mylearning")()  Method 

Use ordinary method calls , Or use getattr You can call this method

bo.mylearning()

getattr(bo, "mylearning")()

hasattr Determine whether the object has corresponding attributes

class M211Vip1:

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


    def welcome(self):
        print(" Congratulations on joining the organization !!!!!")


    def learning(self):
        print(" Is opening up the gap with others ......")

bo = M211Vip1(" wave ", "3")
name = getattr(bo, "name")  #  Map the string to the instance variable 

if hasattr(bo, "name"):
       print(" Yes name attribute ....")
else:
       print(" no name attribute ....")

delattr Delete the specified attribute

    # 4、delattr Delete the specified attribute 
    delattr(bo, "name")
    # print(bo.wkage)
    
    if hasattr(bo, "name"):
        print(" Yes name attribute ....")
    else:
        print(" no name attribute ....")