What does the new method do in the context of Python language?

__new__ is a class method responsible for creating a new instance of the class. It is called before __init__ and determines which object will be returned. It is most often used for creating unique objects (Singleton) or immutable objects (like tuple or str).

class Singleton:
    _instance = None

    def __new__(cls):
        # Check if an instance already exists
        if cls._instance is None:
            # If not, create it by delegating to the parent class (object)
            cls._instance = super().__new__(cls)
        # Return the existing or newly created instance
        return cls._instance

# Usage examples
s1 = Singleton()
s2 = Singleton()

# Expected result: True
print(s1 is s2)

Comparison of __new__ and __init__:

• __new__:

  • Static method (cls is the first argument).
  • Called BEFORE the instance is created.
  • Returns the created instance.

• __init__:

  • Instance method (self is the first argument).
  • Called AFTER the instance is created.
  • Does not return a value (implicitly returns None).
  • Used for initializing attributes of the created object.