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1. Create Class & Object2. Instance vs Class Variables3. Constructors in Python Classes4. Single Inheritance5. Multiple Inheritance6. Multilevel Inheritance7. Polymorphism with Methods8. Method Overloading Simulation9. Encapsulation with Getters/Setters10. Abstraction with ABC11. Operator Overloading12. Custom Iterator13. Class Methods14. Static Methods15. Composition Example16. Aggregation Example17. Private Variables18. Magic Methods Overview19. Object Cloning20. Custom Exceptions21. Class Decorator22. Prototype Pattern23. Singleton Pattern24. MRO (Method Resolution Order) Demo25. Polymorphism (Duck Typing)

Magic Methods Overview in Python

Show common magic methods like __str__ and __len__.

IntermediateObject-Oriented ProgramsExample 18 of 25
magic-methods-overview.py
1# Program to demonstrate some magic methods
2

3class BookCollection:
4    def __init__(self, books):
5        self.books = books
6

7    def __len__(self):
8        return len(self.books)
9

10    def __str__(self):
11        return ", ".join(self.books)
12

13bc = BookCollection(["Python 101", "OOP in Python"])
14print(len(bc))
15print(bc)

Output

2
Python 101, OOP in Python

What's going on

Implementing __len__ and __str__ customizes how len() and print() behave for the class.

After this program

If the idea is still fuzzy, read Day 11: Classes and Objects in the Python course. For a short check, try the Python quiz (300 questions). Stay with all 25 object-oriented programs, or see every topic on Python exercises.

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