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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)

Constructors in Python Classes

Use the __init__ constructor to initialize new objects with default and custom values.

BeginnerObject-Oriented ProgramsExample 3 of 25
constructors-in-python-classes.py
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1# Program to demonstrate constructors
2

3class Rectangle:
4    def __init__(self, width=1, height=1):
5        self.width = width
6        self.height = height
7

8    def area(self):
9        return self.width * self.height
10

11default_rect = Rectangle()
12custom_rect = Rectangle(4, 5)
13

14print("Default area:", default_rect.area())
15print("Custom area:", custom_rect.area())

Output

Default area: 1
Custom area: 20

What's going on

__init__ allows default parameter values and custom initialization when creating objects.

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