📘 Lesson · Lesson 84

Magic Methods (Dunder)

What are Dunder Methods?

💡 At a Glance

Magic methods (or "dunder" methods) start and end with double underscores. They let your objects work with built-in operations like +, len(), print().

Example

Python

class Book:
    def __init__(self, pages):
        self.pages = pages
    def __str__(self):
        return f"Book with {self.pages} pages"
    def __len__(self):
        return self.pages
    def __add__(self, other):
        return Book(self.pages + other.pages)

b1 = Book(100)
b2 = Book(50)
print(b1)              # __str__
print(len(b1))         # __len__
print((b1 + b2).pages) # __add__

Book with 100 pages 100 150

Summary

__init__ sets up the object; __str__ controls print(); __len__ controls len().
__add__ lets you use + on your objects.

Dunder Methods क्या हैं?

💡 एक नज़र में

Magic methods (या "dunder") double underscores से शुरू और खत्म होती हैं। ये आपके objects को +, len(), print() जैसी built-in operations के साथ काम करने देती हैं।

Example

Python

class Book:
    def __init__(self, pages):
        self.pages = pages
    def __str__(self):
        return f"Book with {self.pages} pages"
    def __len__(self):
        return self.pages
    def __add__(self, other):
        return Book(self.pages + other.pages)

b1 = Book(100)
b2 = Book(50)
print(b1)              # __str__
print(len(b1))         # __len__
print((b1 + b2).pages) # __add__

Book with 100 pages 100 150

सारांश

__init__ object setup करता; __str__ print() control; __len__ len() control करता है।
__add__ आपके objects पर + use करने देता है।

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