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.
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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 simple, keep 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:
- Users don’t want to waste time. They expect a frictionless experience with straightforward, intuitive user flows, jargon-free naming, and quick results.
- A simpler software structure makes testing, including also automated testing, easier and more effective.
- Reduced codebase complexity makes maintenance and onboarding of new team members mid-project easier and faster.
KISS example in product development
An example of using the KISS (Keep It Simple, Stupid) principle in software development can be seen in the design of a user interface for an application. Let’s consider a task management app, which requires a method for users to add new tasks.
Instead of designing an elaborate multi-step wizard with numerous options for categorizing, prioritizing, and scheduling each task, applying the KISS principle would lead to the creation of a simple, straightforward interface. Here, users could add a new task with a minimal form: just a field for the task description and a submit button. Advanced options like setting priorities or deadlines could be hidden behind an optional “More options” button, which users can click to access these features only if needed.
This approach keeps the interface clean and uncluttered, reducing the cognitive load on users and making the application easier to use and understand. It simplifies both the user’s interaction with the app and the underlying code, which in turn facilitates easier maintenance and fewer chances for errors. This not only enhances the user experience but also aligns with the core functionality of quickly adding tasks, directly reflecting the KISS principle by focusing on simplicity and essential features.
What is YAGNI principle?
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:
- Better developer performance: The team focuses on delivering the current requirements effectively. They don’t spend time and effort on guesses.
- 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.
YAGNI example in product development
An example of applying the YAGNI (You Aren’t Gonna Need It) principle in software development can be illustrated during the development of a new e-commerce platform. Suppose the initial project scope includes basic functionalities like product listing, shopping cart, and checkout process.
While brainstorming, the development team might consider integrating a sophisticated recommendation engine that suggests products based on user behavior and purchasing history. This feature, while potentially valuable, is complex and time-consuming to develop.
Applying the YAGNI principle, the team would decide against building the recommendation engine during the initial development phase. Instead, they focus on implementing and perfecting the core functionalities that are immediately necessary—product listing, shopping cart, and checkout. The team would only consider developing the recommendation engine in a future iteration if data and user feedback indicate a clear demand for more personalized shopping experiences.
This approach prevents the team from spending resources on features that might not be needed immediately or ever, thereby saving time and money and reducing the risk of feature bloat. It ensures the project remains focused and lean, prioritizing direct customer needs over speculative functionality.
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.
DRY example in product development
An example of applying the DRY (Don’t Repeat Yourself) principle in software development can be seen in managing user authentication across different parts of an application.
Suppose a web application has multiple components that require user authentication, such as the login system, user profile page, and settings page. Instead of writing separate authentication code for each component, which can lead to redundancy and increased maintenance overhead, the DRY principle would guide developers to create a single authentication module or service.
This centralized authentication service would handle all user verification processes and can be called by various parts of the application. Whenever a user tries to access their profile or modify settings, this service is invoked to check if the user is logged in and has the necessary permissions.
By implementing a single authentication service, the codebase becomes cleaner, easier to understand, and maintain. If changes are needed, such as updating the security protocols or modifying the login mechanism, these can be made in one place, reducing the likelihood of errors and inconsistencies across different parts of the application. This approach not only saves development time but also ensures that the system’s security practices are uniformly applied, enhancing overall security.
How KISS, DRY, and YAGNI 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.
FAQ:
How can teams effectively balance the KISS and DRY principles without oversimplifying or compromising the functionality of the software?
Balancing the KISS and DRY principles requires careful consideration of the project’s requirements and the potential for future scalability. Teams should focus on keeping designs as simple as possible to reduce complexity but avoid oversimplification that might strip essential features or flexibility. They should employ DRY to eliminate redundancy without creating overly abstract solutions that obscure the code’s purpose. Regular reviews and refactorings are crucial to maintaining this balance, ensuring that simplifications do not compromise the system’s functionality and that avoiding redundancy does not lead to overly complex abstractions.
Are there specific tools or techniques that can help in the implementation of the YAGNI principle to better manage project scopes and avoid overengineering?
Implementing the YAGNI principle effectively can be supported by various Agile project management tools and techniques. For instance, using user stories and acceptance criteria can help define what is necessary for the current iteration. Tools that support Agile methodologies, like Jira or Trello, can help teams stay focused on the current sprint’s goals by limiting the visibility of future requirements. Techniques such as continuous integration and regular code reviews also encourage developers to focus only on the functionalities required at the moment, thereby adhering to the YAGNI principle.
What are some common challenges or pitfalls that teams might face when trying to implement these principles and how can they be overcome?
A common challenge in implementing KISS, YAGNI, and DRY is the temptation to anticipate future needs, which can lead to overcomplicated designs or premature optimization. Teams might also struggle with finding the right level of abstraction to effectively apply DRY without reducing code clarity. To overcome these challenges, teams should foster a culture of open communication and regular feedback through Agile ceremonies like sprint reviews and retrospectives. Training sessions and workshops on these principles can also equip team members with a better understanding of how to apply them effectively without falling into common traps such as overdesigning or underestimating the complexity needed.
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