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Python del keyword

Python : delete vs del

Last Updated : 27 Dec, 2019

Both __delete__ and __del__ are dunder or magic methods in Python. Dunder or magic methods in Python are the methods having two prefix and suffix underscores in the method name. Dunder here means “Double Under (Underscores)”. These are commonly used for operator overloading.

del

__del__ is a destructor method which is called as soon as all references of the object are deleted i.e when an object is garbage collected.

Syntax:

  def __del__(self):      body of destructor      .      .

Example: Here is the simple example of destructor. By using del keyword we deleted the all references of object ‘obj’, therefore destructor invoked automatically.

   # Python program to demonstrate 
# __del__ 
  
  
class Example:  
    
    # Initializing 
    def __init__(self):  
        print("Example Instance.") 
  
    # Calling destructor 
    def __del__(self):  
        print("Destructor called, Example deleted.")  
    
obj = Example()  
del obj  
 
  

Output:

  Example Instance.  Destructor called, Example deleted.

Note : The destructor was called after the program ended or when all the references to object are deleted i.e when the reference count becomes zero, not when object went out of scope.

delete

__delete__ is used to delete the attribute of an instance i.e removing the value of attribute present in the owner class for an instance.

Note: This method only deletes the attribute which is a descriptor.

Syntax:

  def __delete__(self, instance):      body of delete      .      .

Example:

   # Python program to demonstrate 
# __delete__ 
  
  
class Example(object): 
  
    # Initializing 
    def __init__(self): 
        print("Example Instance.") 
  
    # Calling __delete__ 
    def __delete__(self, instance): 
        print ("Deleted in Example object.") 
  
  
# Creating object of Example 
# class as an descriptor attribute 
# of this class 
class Foo(object): 
    exp = Example() 
  
# Driver's code 
f = Foo() 
del f.exp 
 
  

Output:

  Example Instance.  Deleted in Example object.

Difference between delete and del__

Example: A combine example of __del__ and __delete__.

   # Python program to demonstrate 
# __del__ and __delete__ 
  
  
class Example(object): 
  
    # Initializing 
    def __init__(self): 
        self.value = '' 
  
    # deletes an attribute 
    def __delete__(self, instance): 
        print ("Inside __delete__") 
          
    # Destructor 
    def __del__(self): 
        print("Inside __del__") 
      
      
class Foo(object): 
    exp = Example() 
  
# Driver's code 
f = Foo() 
del f.exp 
 
  

Output:

  Inside __delete__  Inside __del__

Python del keyword

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HarshitaSahai

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