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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)

Custom Exceptions in Python

Define and raise custom exception classes in an OOP style.

IntermediateObject-Oriented ProgramsExample 20 of 25
custom-exceptions.py
1# Program to define and use a custom exception
2

3class NegativeAgeError(Exception):
4    pass
5

6def set_age(age):
7    if age < 0:
8        raise NegativeAgeError("Age cannot be negative")
9    print("Age set to", age)
10

11set_age(20)
12# set_age(-5)  # would raise NegativeAgeError

Output

Age set to 20

What's going on

Custom exceptions derive from Exception and add semantic meaning to error conditions.

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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