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Python setattr()

The built-in function setattr() is used to assign the given value to the specified attribute of the specified object.

setattr(object, name, value) #where object indicates whose attribute value is needs to be change

setattr() Parameters:

Takes three parameters. We can say that setattr() is equivalent to object.attribute = value.

Parameter Description Required / Optional
object an object whose attribute has to be set Required
name  attribute name Required
value the value is given to the attribute Required

setattr() Return Value

The setattr() method doesn't return anything it only assign objects attribute value. This function is useful in dynamic programming in such a situation we cannot assign attribute value using the 'dot' operator.

Examples of setattr() method in Python

Example 1: How setattr() works in Python?

class PersonName:
    name = 'Dany'
p = PersonName()
print('Before modification:', p.name)

# setting name to 'John'
setattr(p, 'name', 'John')

print('After modification:', p.name)


Before modification: Dany
After modification: John

Example 2: When the attribute is not found in setattr()

class PersonName:
    name = 'Dany'
p = PersonName()

# setting attribute name to John
setattr(p, 'name', 'John')
print('Name is:', p.name)

# setting an attribute not present in Person
setattr(p, 'age', 23)
print('Age is:', p.age)


Name is: John
Age is: 23

Example 3: Python setattr() exception case

class PersonName:

    def __init__(self):
        self._name = None

    def get_name(self):
        print('get_name called')
        return self._name

    # for read-only attribute
    name = property(get_name, None)

p = PersonName()

setattr(p, 'name', 'Sayooj')


Traceback (most recent call last):
  File "/Users/sayooj/Documents/github/journaldev/Python-3/basic_examples/python_setattr_example.py", line 39, in 
    setattr(p, 'name', 'Sayooj')
AttributeError: can't set attribute