In Python's object-oriented programming model, attributes and methods are fundamental building blocks of a class. They help define the structure and behavior of the objects you create. Attributes store the data related to the object, while methods define what the object can do.

1. What Are Attributes?

Attributes are variables that belong to an object. They are used to store information about the object's state.

Instance Attributes

These are attributes unique to each object and are usually defined in the __init__() method using self.

class Person:
    def __init__(self, name, age):
        self.name = name  # instance attribute
        self.age = age

person1 = Person("Alice", 30)
print(person1.name)  # Output: Alice
print(person1.age)   # Output: 30

Class Attributes

These are shared across all instances of the class.

class Dog:
    species = "Canine"  # class attribute

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

dog1 = Dog("Buddy")
dog2 = Dog("Max")

print(dog1.species)  # Output: Canine
print(dog2.species)  # Output: Canine

2. What Are Methods?

Methods are functions defined inside a class that operate on object data. They always take self as the first parameter to refer to the current object.

class Circle:
    def __init__(self, radius):
        self.radius = radius

    def area(self):
        return 3.14 * self.radius ** 2

circle1 = Circle(5)
print(circle1.area())  # Output: 78.5

3. Special Methods (Magic Methods)

These methods start and end with double underscores, like __init__, __str__, and __len__.

class Book:
    def __init__(self, title):
        self.title = title

    def __str__(self):
        return f"Book Title: {self.title}"

book = Book("Python 101")
print(book)  # Output: Book Title: Python 101

4. Accessing and Modifying Attributes

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

student1 = Student("Rahul")
print(student1.name)     # Output: Rahul

student1.name = "Aman"
print(student1.name)     # Output: Aman

5. Private Attributes

Use a single underscore (convention) or double underscore (name mangling) to indicate private attributes.

class BankAccount:
    def __init__(self, balance):
        self.__balance = balance  # private attribute

    def get_balance(self):
        return self.__balance

account = BankAccount(1000)
print(account.get_balance())  # Output: 1000

6. Calling Methods from Other Methods

class Temperature:
    def __init__(self, celsius):
        self.celsius = celsius

    def to_fahrenheit(self):
        return (self.celsius * 9/5) + 32

    def display(self):
        print(f"{self.celsius}°C = {self.to_fahrenheit()}°F")

temp = Temperature(25)
temp.display()  # Output: 25°C = 77.0°F

7. Summary Table

8. Final Thoughts

Understanding attributes and methods is crucial to mastering object-oriented programming in Python. Attributes define the data an object holds, while methods define how that data is manipulated or used. By writing clean, modular classes, you can build scalable and maintainable applications with ease.