Python __init__ vs __new__

In Python, __init__ and __new__ are part of a group of special methods in Python commonly referred to as dunder methods or magic methods. The term "dunder" is short for "double underscore," reflecting the naming convention with double underscores at the beginning and end of the method names.

Python __new__

__new__ method in Python is a special method that's responsible for actually creating a new instance of a class. Think of it as the step where the object itself comes into existence, even before it gets initialized with specific values. It gets called automatically before the __init__ method, which is used to set up the object.

Let's understand this with an example :

class CustomObject:
    def __new__(cls, value):
      
        # Create a new instance
        instance = super().__new__(cls)
        
        # Attach an attribute during creation
        instance.value = value
        return instance


# Creating objects
obj1 = CustomObject(10)
obj2 = CustomObject(20)

print(obj1.value) 
print(obj2.value)  

10
20

Explanation :

• instance = super().__new__(cls): Calls the parent class’s __new__ to create an instance.
• instance.value = value: Adds a custom attribute during creation.
• return instance: Returns the newly created instance; object creation fails if not returned.

Python __init__

__init__ method in Python is a special method known as the initializer or constructor. It is called automatically when a new instance (object) of a class is created. Its primary purpose is to initialize the object's attributes (or set up its state) after the object has been created.

Let's understand this with an example :

class SimpleObject:
    def __init__(self, value):
      
        # Initialize the instance
        self.value = value


# Creating objects
obj1 = SimpleObject(10)
obj2 = SimpleObject(20)

print(obj1.value)  
print(obj2.value) 

10
20

Demonstration of __new__ and __init__ in Instance Creation

In Python, __new__ and __init__ are two special methods that play distinct roles in the object instantiation process:

class MyClass:
    def __new__(cls, *args, **kwargs):
      
        print("GeeksforGeeks")
        
        # Calling the parent class's __new__ method to create the instance
        instance = super().__new__(cls)
        return instance

    def __init__(self, value):
        # This method initializes the object after it's created
        print(f"{value}")
        self.value = value

# Create an instance of MyClass
obj = MyClass(10)

GeeksforGeeks
10

Explanation:

• __new__ method is responsible for creating the instance. It’s called before __init__ and is where the object itself is actually created.
• The super().__new__(cls) call creates the new instance, and then it’s returned so that Python can continue with the initialization.
• After the instance is created by __new__, the __init__ method is called to initialize the object’s attributes.

Major Differences between __new__ and __init__