intermediateOOP

Classes & Objects

Object-Oriented Programming: define classes, create objects, and manage state.

In this lesson

01Defining a Class
02Instance vs Class Variables

01Defining a Class

Classes are blueprints for objects. They bundle data (attributes) and behavior (methods).

Python

1class Dog:
2    def __init__(self, name, breed):
3        self.name = name
4        self.breed = breed
5    
6    def bark(self):
7        return f"{self.name} says Woof!"
8    
9    def __str__(self):
10        return f"{self.name} ({self.breed})"
11
12rex = Dog("Rex", "German Shepherd")
13print(rex.bark())
14print(rex)

Output

Rex says Woof!
Rex (German Shepherd)

02Instance vs Class Variables

Instance variables are unique to each object; class variables are shared across all instances.

Python

1class Employee:
2    company = "TechCorp"   # class variable
3    
4    def __init__(self, name, salary):
5        self.name = name       # instance variable
6        self.salary = salary
7
8emp1 = Employee("Alice", 80000)
9emp2 = Employee("Bob", 90000)
10
11print(emp1.company)   # TechCorp
12print(emp2.company)   # TechCorp
13print(emp1.salary)    # 80000

Output

TechCorp
TechCorp
80000

Sets

Inheritance & Polymorphism