Python's magic methods (or dunder methods) are special methods used to define the behavior of objects, which start and end with a double underscore. 1. They enable objects to respond to built-in operations, such as addition, comparison, string representation, etc.; 2. Common use cases include object initialization and representation (__init__, __repr__, __str__), arithmetic operations (__add__, __sub__, __mul__) and comparison operations (__eq__, __lt__); 3. When using it, make sure that their behavior meets expectations. For example, __repr__ should return expressions of refactorable objects, and arithmetic methods should return new instances; 4. Over-use or overload operators in confusing ways should be avoided to keep the code intuitive and easy to read.
Python magic methods, also known as dunder methods (short for "double underscore"), are special methods that begin and end with double underscores. They allow you to define how objects of your class behave in response to built-in operations like addition, comparison, string representation, and more. These methods aren't meant to be called directly by you; instead, they're automatically invoked when you use certain language constructs.

Common Use Cases for Magic Methods
Magic methods are used to emulate the behavior of built-in types or to customize how your objects interact with Python's syntax. Here are a few common scenarios:

Object Initialization and Representation:
__init__
,__repr__
, and__str__
help control how an object is created and displayed.-
Arithmetic Operations:
Methods like__add__
,__sub__
, and__mul__
let your objects support math operations using familiar operators like-
, and*
. Comparison Operators:
__eq__
,__lt__
, and others allow your objects to work with comparisons like==
,, etc.
How to Use Magic Methods Effectively
When defining magic methods, it's important to match their expected behavior closely. For example:
- If you implement
__repr__
, make sure it returns a valid Python expression that could recreate the object. - When implementing arithmetic methods, return a new instance rather than modifying the existing one unless mutation is clearly intended.
Here's a simple example:
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 __repr__(self): return f"Point({self.x}, {self.y})"
In this case, two Point
instances can be added together using the
operator, and printing the object giving a useful representation.
Some things to keep in mind:
- Not all magic methods need to be defined — only those relevant to your class.
- Always check if the other operand is of a compatible type inside methods like
__add__
. - Returning
NotImplemented
from a magic method allows other classes to try handling the operation.
When to Avoid Overusing Magic Methods
While powerful, magic methods can make code harder to read if overused or used unpredictably. For instance:
- Avoid giving
__str__
a different meaning than what users expect. - Don't overload operators in ways that confuse their usual semantics — like using
Stick to intuitive implementations so that anyone reading your code doesn't have to guess what's going on behind the scenes.
Basically that's it.
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