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KISS, YAGNI, DRY – three principles that every developer should know about

Keep it simple, stupid (KISS), you aren’t gonna need it (YAGNI), and don’t repeat yourself (DRY) are some of the most powerful digital product design principles. They lay the foundations for best practices that developers use to build better products every day. In this article, we’ll explain each of these methods, including the explanation of why they’re important elements of a reliable development process.

Keep it simple, stupid (KISS), you aren’t gonna need it (YAGNI), and don’t repeat yourself (DRY) are some of the most powerful digital product design principles. They lay the foundations for best practices that developers use to build better products every day. In this article, we’ll explain each of these methods, including the explanation of why they’re important elements of a reliable development process.

Table of contents
  1. What is the KISS principle?
  2. Advantages of the KISS principle
  3. What is YAGNI?
  4. Why use the YAGNI principle in software development?
  5. Understanding the DRY principle
  6. How does the DRY principle benefit products?
  7. How KISS, YAGNI, and DRY help you build better products

Most people in the software business are familiar with the Agile manifesto principles, and while the manifesto is a great starting point for establishing an effective delivery process, there is much more to it than that (and besides, everything has to have a fancy acronym) including, – test-driven development (TDD), SOLID, full-cycle product development (FCPD), as well as KISS, YAGNI, and DRY that we’ll cover today.

What is the KISS principle?

According to the keep it simple, stupid principle the key to building a successful product is simplicity. The KISS method applies to the design and development of digital products, but it’s also widely used in other fields, such as management or engineering.

It was actually first noted in the U.S. Navy in 1960. And the idea that it’s generally more effective to keep things simple rather than complex, is much older. It’s probably safe to say that minimalism doesn’t have one founding father or mother, so let’s take this quote from Leonardo da Vinci as an example: Simplicity is the ultimate sophistication.

KISS is also used as an acronym for keep it short and simplekeep it short and sweet and keep it simple and straightforward. However, all these variations refer to the same approach.

Advantages of the KISS principle

In the digital product development context, the keep it simple, stupid principle has a huge impact on overall product success:

  1. Users don’t want to waste time. They expect a frictionless experience with straightforward, intuitive user flows, jargon-free naming, and quick results.
  2. A simpler software structure makes testing, including also automated testing, easier and more effective.
  3. Reduced codebase complexity makes maintenance and onboarding of new team members mid-project easier and faster.

What is YAGNI?

The you aren’t gonna need it (YAGNI) principle comes from Extreme Programming. It requires software developers to work on functionalities when they’re actually needed, not when they assume or foresee that something might be useful in the future. The YAGNI principle is also important when implementing Agile, as the framework states that the development team should focus only on the current iteration in order to deliver the agreed scope in time.

Why use the YAGNI principle in software development?

The main goal of the YAGNI principle is to avoid spending time and money on overengineering things that you think you will need later on. Because in the end, it usually turns out that you don’t need it, or that what you need is different from what you expected.

The primary benefit of using YAGNI is a more cost-optimized product development process due to:

  1. Better developer performance: The team focuses on delivering the current requirements effectively. They don’t spend time and effort on guesses.
  2. More flexible codebase: You don’t have to find ways to use suboptimal solutions that you had already developed before you had the full picture.

Understanding the DRY principle

DRY stands for don’t repeat yourself and recommends reducing the repetition of software patterns. By eliminating redundancies in process and logic, engineers lower technical debt and improve the maintainability of the code – both of which are important cost factors, especially in the long term. What’s important, DRY should be applied across the whole system, including not only in the codebase but also in testing and documentation.

The DRY principle states that Every piece of knowledge must have a single, unambiguous, authoritative representation within a system (the quote comes from the book “The Pragmatic Programmer” written by Andrew Hunt and David Thomas). It requires programmers to use abstraction to remove characteristics, in order to be able to reuse an element in different parts of the application.

How does the DRY principle benefit products?

The DRY principle ensures that any modification of a single element of a system does not require a change in other, logically unrelated elements. So it’s an effective way of streamlining the development process. In addition, elements that are logically related change predictably and uniformly, which keeps them in sync.

How KISS, YAGNI, and DRY help you build better products

KISS, YAGNI, and DRY are powerful alone, but better together. By applying them in your product development process you will:

  • Get a product with a better user experience.
  • Increase the efficiency of the development team in the short and long term.
  • Create a simple, maintainable, and flexible codebase.
  • Avoid legacy code where possible.
  • Optimize the cost of developing new features and system maintenance.
  • Enable your developers to improve their ways of working and communication, which at the end of the day, will increase product quality and employee satisfaction.

These product design principles are sets of guidelines that have proven effective over the years. They are widely known among experienced developers, solution architects, and product designers, but for some reason, they rarely make it to business decision-makers. And that’s a missed opportunity.

As you can see, in the end, the benefits of KISS, YAGNI, and DRY are strongly tied to the overall product’s success and the organization’s KPIs. Therefore, product owners, project managers, and C-level executives who understand the potential of these design principles, and have their teams apply them in every iteration, have higher chances of market success.

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