Key OOP Principles

The fundamental principles of Object-Oriented Programming include:

• Classes
• Objects
• Attributes
• Methods
• Constructors
• Inheritance
• Polymorphism

Benefits of OOP

• Modularity, which simplifies debugging
• Code reuse through inheritance
• Flexibility via polymorphism
• Enhanced problem-solving capabilities
• Improved productivity

What Are Classes?

A class serves as a user-defined blueprint from which objects are instantiated. Similar to a house blueprint, which provides a visual guide of the house's design, classes define the structure and behavior of objects. In Python, a class is created using the class keyword, while objects are instantiated using the class constructors.

For instance, consider a Bank_Account class where we can declare class attributes. Next, we will delve into class attributes.

What Are Objects?

An object is essentially a bundle of data (attributes) and methods (functions) that operate on that data. In Python, an object can have both attributes and methods. When we instantiate a class, we create an object, which can be thought of as an instance of that class.

To create an object in Python, you simply call the class name followed by parentheses, similar to invoking a function. Each object has its own attributes and methods, which are independent of other objects of the same class.

Class Attributes

In Python, class attributes are variables defined within a class. When a new object of the class is created, these attributes and methods are associated specifically with that object. You can access class attributes using the dot notation.

For example, if you assign the object of the class to a variable, you can access its attributes by appending a dot followed by the attribute name. Class attributes differ from instance attributes, which are specific to individual instances of the class.

Instance Attributes

Instance attributes are defined within the methods of a class, unlike class attributes, which are declared outside. Next, we will explore class methods.

Class Methods

Class methods are defined within a class and perform specific tasks related to the class. They are similar to regular functions but are associated with the class itself.

To illustrate the necessity of class methods, consider a game class with methods such as Attack, Health, and Lives. Each method performs a distinct function that aids in code organization and debugging.

Below is an example code snippet of a Bank_Account class demonstrating class attributes and methods:

class Bank_Account:

def __init__(self):

self.balance = 0

def deposit(self, amount):

self.balance += amount

def withdraw(self, amount):

self.balance -= amount

def display_balance(self):

print(f"Your current balance is: ${self.balance}")

Static Methods

Static methods are similar to class methods but are not tied to the class or its instances. They do not require class instance creation and operate independently of the class state.

Here’s how static methods differ from class methods:

• Static methods do not require knowledge of the class or its attributes.
• Class methods are aware of the class and its attributes.

Static methods are declared using the @staticmethod decorator, while class methods require the self argument.

Constructors in Classes

A constructor is a special method invoked when an object is created. It initializes object attributes and can accept parameters to set initial values.

class Account:

def __init__(self, name, account_number):

self.name = name

self.account_number = account_number

self.balance = 0

The constructor allows you to create objects with dynamic attributes rather than hardcoded values.

The Four Pillars of OOP

Now that we’ve covered the basics of Python OOP, let’s explore its four core principles: Inheritance, Polymorphism, Abstraction, and Encapsulation. This article will focus on Inheritance and Polymorphism.

Inheritance in OOP

Inheritance represents an IS-A relationship in OOP. Just as children inherit traits from their parents, a subclass can inherit attributes and methods from a parent class. For instance, a Bank_Employee class can inherit from a Bank_Account class, enabling access to its public attributes and methods.

Polymorphism in OOP

Polymorphism allows functions with the same name to behave differently based on context. This versatility is a fundamental aspect of OOP.