Python Object-Oriented Programming

What Is Object-Oriented Programming?

Object-oriented programming, or OOP, is a way to organize code around objects. An object groups data and behavior together. A class is the blueprint used to create objects.

class Student:
    def __init__(self, name, score):
        self.name = name
        self.score = score

    def has_passed(self):
        return self.score >= 35

The class describes what a student object should have and what it can do.

Creating Objects

An object is also called an instance.

student = Student("Asha", 88)

print(student.name)
print(student.has_passed())

student.name reads an instance attribute. student.has_passed() calls a method.

The __init__ Method

__init__ runs when a new object is created. It is commonly used to store starting values.

def __init__(self, name):
    self.name = name

The first parameter, self, refers to the current object. Python passes it automatically when you call a method through an object.

Instance Attributes And Methods

Instance attributes belong to a specific object.

first = Student("Asha", 88)
second = Student("Riya", 72)

Each object has its own name and score.

Methods are functions defined inside a class. They usually use self to read or update the current object’s data.

def improve(self, points):
    self.score += points

Class Attributes

A class attribute belongs to the class and is shared by instances unless overridden.

class Student:
    school = "QuizNiva Academy"

Use class attributes for values that should be common across all instances.

Common Mistakes

A common mistake is forgetting self in a method definition.

def has_passed():
    return self.score >= 35

Instance methods need self as the first parameter.

Another mistake is putting changing data in a class attribute when it should belong to each object. If every object needs its own value, use an instance attribute such as self.score.

Quick Summary

• A class is a blueprint.
• An object is an instance of a class.
• __init__ sets up new objects.
• self refers to the current object.
• Instance attributes belong to one object.
• Methods are functions inside classes.
• Class attributes are shared through the class.

Practice Quiz

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