Neetcode.io – Object Oriented Design Patterns

Design patterns are a way to solve commonly occurring problems in software engineering. They are reusable, tested solutions to certain software design problems. They are not cookie-cutter solutions, and developers using them can tailor them to address the specific problem at hand.

Let’s start with a brief overview of the four pillars of object-oriented programming – abstraction, polymorphism, inheritance, and encapsulation (a.k.a. A-P-I-E).

Abstraction – It’s about capturing the essence of real-world entities by focusing on their crucial characteristics. Abstraction helps in managing complexity and ensuring a clean design.

Polymorphism – This is the ability of objects to assume various forms and behaviors. It’s the essence of flexibility in OOP and leads us towards certain design principles we’ll touch on shortly.

Inheritance – A mechanism where one class inherits attributes and behaviors from another, fostering code reusability.

Encapsulation – Bundling data and the methods that operate on that data into one unit, it helps in keeping the internal details under wraps and ensures controlled interactions.

The case for design patterns
A-P-I-E is foundational, but the software engineering realm often requires more nuanced solutions. This is where design patterns come into play. They complement A-P-I-E, bridging the gap between basic OOP concepts and complex challenges. Built upon the SOLID design principles, design patterns are like evolved strategies that are tried, tested, and shared by the developer community. Instead of a lengthy walkthrough, just naming a known design pattern can bring everyone on the same page. It streamlines collaboration and boosts efficiency.

Think of it this way: while constructing a building, understanding the basics like bricks, cement, and steel (A-P-I-E in our context) is crucial. But, it’s the architectural blueprints and patterns that ensure the building stands tall, is functional, aesthetic, and safe. Similarly, while A-P-I-E sets the groundwork, design patterns are those architectural blueprints for software, ensuring it’s resilient, scalable, and maintainable.

One might wonder, why not just reinvent solutions when faced with new challenges? Well, consistently trying to reinvent the wheel for recurrent software challenges can be a resource drain. Instead of investing time in crafting a new solution from scratch, leveraging a design pattern that’s already been through the rigors of multiple real-world tests can save both time and effort. Plus, it brings with it the wisdom of countless developers who have refined and endorsed it.

The key takeaway? It’s not about picking between A-P-I-E, design principles, or design patterns; it’s about understanding their synergy.

What to Expect from the Course
This course takes a hands-on and a practical approach. We aim to help you understand why design patterns are essential and what drives their creation in a compendious manner. The patterns we’ll be diving into include

Behavioral Patterns

Strategy
Observer
Creational Patterns

Factory
Builder
Singleton
Structural Patterns

Facade
Adapter
Decorator

Each article will follow this structure

1. Motivation – Introducing a specific problem and looking at potential solutions, leading us to the need for a refined design pattern.

2. The Solution – Showcasing the design pattern and emphasizing its strengths over traditional solutions.

3. Design and Implementation – Detailed UML diagrams will be provided, accompanied by code snippets in multiple languages (JavaScript, Java, C++, and Python) with annotations to guide you. Not only this, but language-specific notes are included to help understand implementation differences among these four languages.

4. Limitations and Pitfalls – Addressing scenarios where a pattern might not be the best fit.

5. Classic Use Cases – Examples of real-world applications for each pattern.

6. Closing Notes – Summing up the design principles each pattern embodies and reflecting on their importance.