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What are Design Patterns in System Design?

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Prerita Agarwal
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23 Jul, 2024 @ 01:30 PM


Design patterns are like recipes that help people build things in a way that has been proven to work really well.

Imagine we want to build a castle out of some building blocks. We can start by randomly putting bricks together, but it might not be very strong or look very nice. But if we follow a particular set of instructions that others have successfully used before to construct castles, we have a higher chance of building a robust and visually pleasing castle.

Similarly, in software and website development, designers commonly use design patterns to build software and websites in a reliable, easy-to-understand, and efficient way.

For example, a common design pattern is called "Model-View-Controller" or "MVC". This design pattern helps software developers separate parts of the code that controls how things look from the part that controls how things work. This way, if changes need to be made to the code in the future, they can be done without accidentally causing problems in other parts of the code.

So just like building blocks help us to build a sturdy and great-looking castle, design patterns help developers to build robust and efficient software or websites.

Design Patterns in System Design


In this 📝 blog, we're going to 🤔 learn about what are design patterns 🤷‍♂️, why they're important, and their various types 📚. Are you ready to 🧠 learn? Let's get started! 💪

Gang of Four and Their Role in Design Patterns

The Gang of Four (GoF) is a group of four computer scientists – Eric Gamma, Richard Helm, Ralph Johnson, and John Vlissides – who authored the book "Design Patterns: Elements of Reusable Object-Oriented Software."

The book written by the Gang of Four is called the "GOF Book" and is considered the foremost source of information on software design patterns.

It describes 23 design patterns that address common software design problems in object-oriented programming. Patterns are classified into three categories: compositional, structural, and behavioral. These patterns have been widely used by software developers around the world, as these patterns help in creating better software that is easier to maintain.

The Gang of Four books is related to design patterns because this influential book helped popularize the use of design patterns in software development.

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What does the design pattern consist of?

In software development, a design pattern is a reusable solution to a common problem that arises during software design. A design pattern consists of a set of rules or guidelines that help developers solve a particular problem more efficiently and effectively.

According to the book 'Design Patterns,' a pattern has four main components. These components usually consist of the following:

  • Problem: This is a description of the specific problem the pattern is designed to solve. It outlines the requirements and constraints of the problem.
  • Workaround: This is the recommended workaround for the issue. It describes the elements and relationships of the solution, along with the reasoning behind the solution.
  • Consequences: It describes the advantages and disadvantages of using the pattern. It also includes any trade-offs or compromises that may need to be made when using the pattern.
  • Examples: Examples are practical illustrations that demonstrate how a pattern can be applied in real-world situations. They explain how the pattern works and provide guidance on how to apply it to real-world scenarios.

Why and When to Use Design Patterns?

Design Patterns are like templates or blueprints for software development. Just like a builder uses a blueprint to build a house, developers use design patterns to build software applications.

So, why should we use Design Patterns? Well, they make software development more efficient and easier to maintain. When developers use design patterns, they don't have to start from scratch every time they build a new application. They can reuse existing designs and adapt them to the specific needs of each project.

Think of it this way - if we were making a sandwich, we wouldn't have to think about making the bread from scratch every time. To make sandwiches quickly and easily, all we have to do is follow a recipe or use pre-made bread. Design patterns work the same way in software development.

Design patterns are useful when dealing with complex systems, solving common problems, improving maintainability, and collaborating in development environments. They help developers solve problems efficiently and effectively while promoting good coding practices.

Types of Design Patterns

There are three types of design patterns:

  1. Creational patterns: These patterns are concerned with the process of creating objects, including their construction and initialization. 
    Examples of creational patterns include Singleton, Factory Method, Abstract Factory, Builder, and Prototype.
  2. Structural patterns: These patterns deal with the composition of classes and objects to form larger structures. 
    Examples of structural patterns include Adapter, Bridge, Composite, Decorator, Facade, Flyweight, and Proxy.
  3. Behavioral patterns: These patterns describe how classes and objects interact with each other and distribute responsibilities among themselves to accomplish specific tasks.
    Examples of behavioral patterns include Chain of Responsibility, Command, Interpreter, Iterator, Mediator, Memento, Observer, State, Strategy, Template Method, and Visitor.

Each type of design pattern has its own strengths and weaknesses, and developers must choose the appropriate pattern based on the problem at hand.

Benefits of Using Design Patterns

Following are the benefits of using design patterns in software development:

  • Reusability: Design patterns offer ready-made solutions that can be reused in different parts of the code, saving time and effort.
  • Scalability: Patterns help create code that can be easily modified and expanded as the software grows.
  • Flexibility: Design patterns help decouple components, making them more flexible and easier to replace or modify without affecting the rest of the system.
  • Consistency: Patterns provide a common language and structure, helping developers to follow best practices and keep the code consistent and organized.
  • Communication: By using patterns, it is easier for developers to communicate and collaborate on complex projects.
  • Time and cost savings: Design patterns can speed up development and reduce the need for extensive testing, saving time and money.

Frequently Asked Questions

What is the difference between a creational, structural, and behavioral design pattern?

Creational patterns are concerned with object creation, structural patterns deal with object composition, and behavioral patterns characterize the interactions between objects.

How do you choose the right Design Pattern for a specific problem?

To choose the right Design Pattern for a specific problem, developers should consider the problem domain, system requirements, and scalability.

Are there any disadvantages or drawbacks to using Design Patterns in software development?

The disadvantages of using Design Patterns can include increased code complexity, potential misuse, and reduced flexibility. However, the benefits of using Design Patterns typically outweigh the drawbacks.


In this blog, we explored the concept of Design Patterns in software development. We started with an overview of what design patterns are and their importance in system design. We also discussed the Gang of Four, authors of the book "Design Patterns: Elements of Reusable Object-Oriented Software" which is considered as a definitive guide to design patterns.

We explained that a design pattern consists of a general problem, a solution, and the context in which it is used. These patterns are classified into creational, structural and behavioral.

Next, we discussed the benefits of using design patterns and when and why they should be used in software development.

In short, design patterns are essential in software development and can help developers build more efficient, maintainable, and scalable software systems.

You can also consider our System Design Course to give your career an edge over others. We hope you found this blog helpful. Don't hesitate to drop your feedback in the comments section below. 💬

Topics covered
Gang of Four and Their Role in Design Patterns
What does the design pattern consist of?
Why and When to Use Design Patterns?
Types of Design Patterns
Benefits of Using Design Patterns
Frequently Asked Questions
What is the difference between a creational, structural, and behavioral design pattern?
How do you choose the right Design Pattern for a specific problem?
Are there any disadvantages or drawbacks to using Design Patterns in software development?