Dunder or Magic Methods

Python's __magic__ (or dunder) methods are special methods that start and end with double underscores. They're used to implement operator overloading and to define the behavior of custom classes with built-in functions.

Here’s a list of useful and commonly encountered magic methods:

🔧 Object Construction & Representation

Method	Purpose
`__init__(self, ...)`	Constructor. Initializes the object.
`__new__(cls, ...)`	Allocates memory; rarely overridden.
`__str__(self)`	Human-readable string (`str(obj)`, `print(obj)`).
`__repr__(self)`	Official string (`repr(obj)` or in REPL).
`__del__(self)`	Destructor (not commonly used).

🔁 Operator Overloading

Method	Operator	Example
`__add__(self, other)`	`+`	`a + b`
`__sub__(self, other)`	`-`	`a - b`
`__mul__(self, other)`	`*`	`a * b`
`__truediv__(self, other)`	`/`	`a / b`
`__floordiv__(self, other)`	`//`	`a // b`
`__mod__(self, other)`	`%`	`a % b`
`__pow__(self, other)`	`**`	`a ** b`
`__eq__(self, other)`	`==`	`a == b`
`__lt__(self, other)`	`<`	`a < b`
`__le__(self, other)`	`<=`	`a <= b`

📦 Container Behavior

Method	Purpose
`__len__(self)`	Length of the object (`len(obj)`)
`__getitem__(self, key)`	Indexing (`obj[key]`)
`__setitem__(self, key, value)`	Item assignment (`obj[key] = value`)
`__delitem__(self, key)`	Delete item (`del obj[key]`)
`__iter__(self)`	Returns an iterator (`for x in obj`)
`__next__(self)`	Next value in iteration (`next(obj)`)
`__contains__(self, item)`	`in` keyword (`item in obj`)

🎩 Callable & Context Manager

Method	Purpose
`__call__(self, ...)`	Make an object callable like a function (`obj()`)
`__enter__(self)`	Context manager (`with` statement entry)
`__exit__(self, exc_type, exc_val, exc_tb)`	Context manager (`with` statement exit)

💡 Example: Custom Class with Magic Methods

class Point:
    def __init__(self, x, y):
        self.x = x
        self.y = y

    def __add__(self, other):
        return Point(self.x + other.x, self.y + other.y)

    def __str__(self):
        return f"Point({self.x}, {self.y})"

p1 = Point(1, 2)
p2 = Point(3, 4)
print(p1 + p2)  # Uses __add__

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