Python setattr() Function

Python setattr() function is used to set a value to the object's attribute. It takes three arguments an object, a string, and an arbitrary value, and returns none. It is helpful when we want to add a new attribute to an object and set a value to it. The signature of the function is given below.

Signature

Parameters

object: It is an object which allows its attributes to be changed.

name : A name of the attribute.

value : A value, set to the attribute.

All the parameters are required.

Return

It returns None to the caller function.

Let's see some examples of setattr() function to understand its functionality.

Python setattr() Function Example 1

Here, we are adding a new attribute and setting its value by using the setattr() function.

class Student:
    id = 0
    name = ""
    
    def __init__(self, id, name):
        self.id = id
        self.name = name
        
student = Student(102,"Sohan")
print(student.id)
print(student.name)
#print(student.email) product error
setattr(student, 'email','sohan@abc.com') # adding new attribute
print(student.email)

Output:

102
Sohan
[email protected]

Python setattr() Function Example 2

If we don't want to set any value, by default, it can be set None.

class Student:
    id = 0
    name = ""
    
    def __init__(self, id, name):
        self.id = id
        self.name = name
        
student = Student(102,"Sohan")
print(student.id)
print(student.name)
setattr(student, 'email',None) # adding new attribute having None
print(student.email)

Output:

102
Sohan
None

Python setattr() Function Example 3

We can reassign (reset) attribute's value even after calling setattr() function. See the example below.

class Student:
    id = 0
    name = ""
    
    def __init__(self, id, name):
        self.id = id
        self.name = name
        
student = Student(102,"Sohan")
print(student.id)
print(student.name)
setattr(student, 'email',None) # adding new attribute having None
student.email = "Tom@abc.com" # Assigning new value
print(student.email)

Output: