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How do comparison magic methods like __lt__, __le__, __gt__, and __ge__ support custom sorting? How does __contains__ let you customize the behavior of the 'in' operator? How do you implement custom attribute access with __getattr__ versus __getattribute__? How do context manager magic methods __enter__ and __exit__ work, and what does __exit__'s return value control? How do __iadd__ and other in-place operator methods (__isub__, __imul__) differ from their non-in-place counterparts? How does __bool__ (or the legacy __nonzero__) determine an object's truthiness, and what's the fallback if it's not defined? How does __slots__ interact with magic methods and instance attribute storage?
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What is the difference between __new__ and __init__, and when would you override __new__?

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Answer

__new__(cls, ...) is a static method that actually creates and returns the new instance (allocating memory), called before __init__. __init__(self, ...) then initializes that already-created instance and returns None. You override __new__ for cases __init__ can't handle: controlling instance creation for immutable types (like subclassing tuple or str), implementing singletons, or returning an instance of a different class.
class Singleton:
    _instance = None
    def __new__(cls, *args, **kwargs):
        if cls._instance is None:
            cls._instance = super().__new__(cls)
        return cls._instance

a, b = Singleton(), Singleton()
print(a is b)  # True
Real-world example A configuration manager implements __new__ to enforce a single shared instance across the entire application, ensuring all code reads the same in-memory config object.

Common follow-ups: Why can't __init__ alone implement a singleton reliably?;How does __new__ interact with immutable types like int subclasses?

Metaclasses & Class Customization;Multiple Inheritance & MRO
All 15 Magic Methods & Operator Overloading questions