delattr() and del() in Python

Difficulty Level : Basic
Last Updated : 14 Nov, 2017

delattr

The delattr() method is used to delete the named attribute from the object, with the prior permission of the object.
Syntax:

delattr(object, name)

The function takes only two parameter:

object :  from which 
the name attribute is to be removed.
name :  of the attribute 
which is to be removed.

The function doesn't returns any value, 
it just removes the attribute, 
only if the object allows it.

The Working : Suppose we have a class by name Geek and it has five students as the attribute. So, using the delattr() method, we can remove any one of the attributes.

# Python code to illustrate delattr()
class Geek:
  stu1 = "Henry"
  stu2 = "Zack"
  stu3 = "Stephen"
  stu4 = "Amy"
  stu5 = "Shawn"
  
names = Geek()
  
print('Students before delattr()--')
print('First = ',names.stu1)
print('Second = ',names.stu2)
print('Third = ',names.stu3)
print('Fourth = ',names.stu4)
print('Fifth = ',names.stu5)
  
# implementing the method
delattr(Geek, 'stu5')
  
print('After deleting fith student--')
print('First = ',names.stu1)
print('Second = ',names.stu2)
print('Third = ',names.stu3)
print('Fourth = ',names.stu4)
# this statement raises an error
print('Fifth = ',names.stu5)

Output:

Students before delattr()--
First =  Henry
Second =  Zack
Third =  Stephen
Fourth =  Amy
Fifth =  Shawn
After deleting fith student--
First =  Henry
Second =  Zack
Third =  Stephen
Fourth =  Amy

When the execution moves to the last line of the program, i.e., when the fifth attribute is called, the compiler raises an error:

Traceback (most recent call last):
  File "/home/028e8526d603bccb30e9aeb7ece9e1eb.py", line 25, in 
    print('Fifth = ',names.stu5)
AttributeError: 'Geek' object has no attribute 'stu5'

del operator

There is another operator in Python that does the similar work as the delattr() method. It is the del operator. Let’s see how it works.

# Python code to illustrate del()
class Geek:
  stu1 = "Henry"
  stu2 = "Zack"
  stu3 = "Stephen"
  stu4 = "Amy"
  stu5 = "Shawn"
  
names = Geek()
  
print('Students before del--')
print('First = ',names.stu1)
print('Second = ',names.stu2)
print('Third = ',names.stu3)
print('Fourth = ',names.stu4)
print('Fifth = ',names.stu5)
  
# implementing the operator
del Geek.stu5
  
print('After deleting fith student--')
print('First = ',names.stu1)
print('Second = ',names.stu2)
print('Third = ',names.stu3)
print('Fourth = ',names.stu4)
# this statement raises an error
print('Fifth = ',names.stu5)

Output:

Students before del--
First =  Henry
Second =  Zack
Third =  Stephen
Fourth =  Amy
Fifth =  Shawn
After deleting fith student--
First =  Henry
Second =  Zack
Third =  Stephen
Fourth =  Amy

The result is the same with an error:

Traceback (most recent call last):
  File "/home/7c239eef9b897e964108c701f1f94c8a.py", line 26, in 
    print('Fifth = ',names.stu5)
AttributeError: 'Geek' object has no attribute 'stu5'

del vs delattr()

Dynamic deletion : del is more explicit and efficient and delattr() allows dynamic attribute deleting.
Speed : If the above programs are considered and run then there is a slight difference between the speed of execution. del is slightly faster in comparison to delattr(), depending on the machine.
byte-code Instructions : del also takes less byte-code instructions in comparison to delattr().

So we conclude the comparison by saying that del is slightly faster than delattr, but when it comes to dynamic deletion of attribute then delattr() has advantage as it is not possible by del operator.

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