The Four Pillars of Object-Oriented Programming: A Comprehensive Guide

In my previous blog series, we explored how Python Pandas simplifies data manipulation and analysis. Now, let's shift our focus to Object-Oriented Programming (OOP), a powerful paradigm that helps organize code and manage complexity in software development. OOP is essential for building modular, reusable, and scalable applications. In this post, we'll start by diving into the Four Pillars of OOP, the key principles that every programmer should know.

Introduction to Object Oriented Programming (OOP)

Object Oriented Programming, simply known as OOP is a programming paradigm that revolves the software design around the two fundamental concepts: objects and classes. Java, Python, C++ are some of the popular OO languages.

An object is something which represents something tangible or intangible in the real world. For example, in a system, an object can represent a BankAccount, Car, Employee, …

Objects have three main characteristics.

• Identity - Helps to identify an object uniquely. 

• Ex: BankAccount – accountNumber

         Car – licensePlate

         Employee – EPF_number

• State/ Attributes - Characteristics/ features of the object.

• Ex: BankAccount – accountNumber, balance, …

        Car – licensePlate, make, model, …

        Employee – EPF_number, nic, name, address, …

• Behavior - What the object can do and how it responds to events

• Ex: BankAccount – depositCash(), withdrawCash(), …

        Car – start(), accelerate(), reverse(), …

       Employee – raiseSalary(), changeManager(), …

A class is a grouping of objects with similar characteristics. Basically, class is the blueprint of an object. 

Ex: Cars can be considered as a class. Although there can be many cars with different names and brands, they share some common properties such as wheels, speedLimit, mileage etc.

Hence, we can say that an object is an instance of a class.

Let’s dive into the four key pillars of OOP. 

                1. Encapsulation

Encapsulation refers to wrapping up of data under a single unit where the data of a particular class are hidden from any other class and can be accessed only via a member function of their class in which they are declared. This is also known as data hiding.

 Ex: An engine of a car is encapsulated within the vehicle’s body. The driver does not need to know about the inner details of the engine to drive the car; the interface is provided by the steering wheel, the pedals etc.

2. Abstraction 

Abstraction of data means only the essential information about the data should be given to the outside world, and the background details or the implementation should be hidden.

Ex: By considering the real-world scenario of a man driving a car, all he knows is that pressing the accelerators will increase the speed of the car, or applying breaks will stop the car, but he does not know the inner implementation mechanism of how the speed is increased upon pressing the accelerator. 

3. Inheritance

Inheritance allows a class to derive from another class and to inherit its attributes and methods. The inherited class is called the parent class, base class or the super class while the class that inherits is called the child class or the derived class. The child class can also contain its own attributes and methods. 

Ex: A car is a subclass of the vehicle class. All cars are vehicles, but not all vehicles are cars. That means the car inherits general characteristics from the vehicle class, like having wheels,  and adds some features like a steering system. 

There are several types of inheritance:

4. Polymorphism

The term polymorphism itself means having many forms. Multiple classes can use the same method name using polymorphism, by redefining these methods for classes derived from them. Inheritance allows objects to override shared parent behaviors with specific child behaviors.

Ex: A man can be a father, husband as well as an employee at the same time.

Why OOP?

·       It ensures code reusability.

·       Enhances productivity.

·       Ensures code flexibility.

·       Changes can be made effortlessly.

·       Real-world problems can be easily solved with OOP.

·       It does not require you to write the basic codes repeatedly.

·       Consistency can be maintained throughout the code.

·       Data hiding feature offers better security.

·       Lowers the development costs.

·       Easy maintenance of codes.

In conclusion, understanding the Four Pillars of Object-Oriented Programming: encapsulation, abstraction, inheritance, and polymorphism is crucial for writing clean, efficient, and maintainable code. These principles provide the foundation for building robust software that can grow and adapt over time. Whether you're designing a small project or a large-scale application, applying these concepts will help you create flexible and reusable code. As you continue your journey in programming, keep these pillars in mind, and you'll find that OOP can be a powerful tool in your development toolkit.