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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)

Instance vs Class Variables in Python

count lives on the class. id lives on each object. Change count once, every instance sees it.

BeginnerObject-Oriented ProgramsExample 2 of 25
instance-vs-class-variables.py
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1# Program to demonstrate instance vs class variables
2

3class Counter:
4    count = 0  # class variable
5

6    def __init__(self):
7        Counter.count += 1
8        self.id = Counter.count  # instance variable
9

10c1 = Counter()
11c2 = Counter()
12

13print("c1.id:", c1.id)
14print("c2.id:", c2.id)
15print("Total objects created:", Counter.count)

Output

c1.id: 1
c2.id: 2
Total objects created: 2

What's going on

The class variable 'count' is shared across all instances, while 'id' is unique per instance.

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