Attributes

Part of the Object Oriented Programming section of Coddy's Python journey — lesson 6 of 64.

Attributes are data or variables that belong to a class or its objects. They store information about the object's state.

There are two types of attributes:

Class attributes - shared by all objects of the class:

class Student:
    school_name = "Python Academy"  # class attribute

Instance attributes - unique to each object:

class Student:
    school_name = "Python Academy"
    
    def set_info(self, name, age):
        self.name = name    # instance attribute
        self.age = age      # instance attribute

Create student objects and set their individual data:

student1 = Student()
student2 = Student()

student1.set_info("Alice", 20)
student2.set_info("Bob", 22)

Access instance attributes (unique to each object):

print(student1.name)    # Alice
print(student2.name)    # Bob
print(student1.age)     # 20

Access class attributes (same for all objects):

print(student1.school_name)    # Python Academy
print(student2.school_name)    # Python Academy
print(Student.school_name)     # Python Academy

Output:

Alice
Bob
20
Python Academy
Python Academy
Python Academy

Key Difference: Class attributes are shared by all objects, while instance attributes are unique to each object. Use self.attribute_name for instance attributes and just attribute_name for class attributes.

Cheat sheet

Attributes are data or variables that belong to a class or its objects.

Class attributes - shared by all objects of the class:

class Student:
    school_name = "Python Academy"  # class attribute

Instance attributes - unique to each object, defined using self:

class Student:
    school_name = "Python Academy"
    
    def set_info(self, name, age):
        self.name = name    # instance attribute
        self.age = age      # instance attribute

Access instance attributes:

student1 = Student()
student1.set_info("Alice", 20)
print(student1.name)    # Alice

Access class attributes:

print(student1.school_name)    # Python Academy
print(Student.school_name)     # Python Academy

Try it yourself

This lesson doesn't include a code challenge.

Test yourself

This lesson includes a short quiz. Start the lesson to answer it and track your progress.

All lessons in Object Oriented Programming

1Fundamentals of OOP

External Files Introduction to OOP Classes vs Objects The self Parameter MethodsAttributesConstructor Method (__init__)Recap - Simple Calculator

4Inheritance

Basic Inheritance The super() Function Method Overriding Multiple Inheritance Method Resolution Order Recap - Employee Hierarchy

7Special Methods

Magic Methods Introduction Operator Overloading Container Magic Methods Recap - Custom List

10Design Patterns Part 1

Intro to design pattern Singleton Pattern Factory Pattern Observer Pattern Strategy Pattern

13Final Challenges

E-learning Platform Banking System Game Character Development Vehicle Rental Service

3Class Properties

Instance vs Class Variables Property Decorators Private Attributes Recap - Bank Account Manager

6Encapsulation

Public, Protected, Private Mem Access Modifiers Information Hiding Property Decorators Advanced Recap - Student Records System

9Advanced Arguments

The *args The **kwarg

12Project: Library Management

Project Overview Book and User Classes

Borrowing System

Search Functionality

Admin Interface

Testing and Integration