The KISS Principle in Software Development — Everything You Need to Know

Keep It Simple, Stupid — The full-form and the fundamental idea behind the KISS principle in software development. Although this principle applies to any aspect of designing, it has great significance when it comes to developing software that is easy to understand and use by the developers and end-users alike.

Despite the growing interest of these principles among developers, there exists a myriad of misinformation and misconceptions. Neglecting this approach may lead to unsatisfactory performance and loss of customer satisfaction, considering the highly competitive industry. According to Compare Metrics and e-tailing group study, 64% of shoppers prefer simplicity in the purchase process.

From the developers’ perspective, complex coding is the root of numerous risks and complications. It not only means wasted efforts but also makes it extremely difficult to implement changes.

In the following sections, we present an overview of the KISS principle in software design, outlining its significance, methods, and more.

What does ‘Simple’ stand for in the KISS Principle?
For a proper understanding of the KISS principle, in software design or otherwise, it’s imperative that we know what ‘Simple’ means in this context.

First, it doesn’t mean ‘easy,’ although applying these principles ultimately leads to ease of access. Simple doesn’t refer to that which is easily doable. Second, implementing simpler codes (or following KISS principles) doesn’t imply that the developers can’t write complex code. Simplicity doesn’t mean that the developer shies away from including necessary complexities. The idea is to make the application ‘as simple as possible’ while including all the functionalities that its purpose demands.

Simple, in the context of the KISS principle, means systems with lesser parts and, more importantly, fewer interconnected parts. Applications must have simple coding and mustn’t comprise of avoidable, interlinked parts.
In this sense, the idea behind the KISS principles translates to an understanding of software development where we neither want less nor more. Here, we wish to have only as much as required — both in terms of coding and features. While the ideator must trim their ideas, the developer must apply the simplest possible coding to actualize this idea.
Thus, business or project owners, for whom the application is developed, also have a role to play in achieving the desired simplicity in software development. Decisions taken with regard to an app’s functionality and design must include the developer working on the same in all the stages. This ensures that demands which unnecessarily increase complexities are avoided.

Why Apply the KISS Principles in Software Design?
Developing an application with simple backend and frontend codes has several advantages. It fosters collaboration as other people on the team can easily understand the original code, enabling successors to work fluently on an existing application.

KISS principles in software development allow developers to tackle the most significant difficulty of software development — implementing changes to the existing code.

First, it makes it easier for the developer to visualize the various aspects of the applications, mentally mapping the possible effects of any change. This involves knowing the dependencies, states, and more.

Second, once the changes are made, it’s easier to test a simple system than an extremely complex one. Moreover, simpler processes allow for greater efficiency in automated testing.

Third, an application that has simpler requirements on the part of the developer and involves simpler components is ultimately more likely to be simple-to-use for the end-user.

Implementing the KISS Principle in Software Development
The KISS Principle can be followed by adhering to a list of DON’T’s as mentioned below:

Avoid Global Functions or Elements
The Global States or Global Variables or simply Globals, refer to those states or variables whose scope extends to the entire application. Moreover, their state can change at run-time — i.e., they are mutable. On the contrary, the scope of locals is limited to some parts of the application.

Although Globals appear to be an easy way to share states between parts of the application without having to pass them through functions, they are detrimental to the implementation of KISS principles.

Globals give rise to significant problems such as Global name collisions, low testability, and concurrency issues. Furthermore, Globals add to the overall complexity of the code. They often act as hidden elements whose change of states is undeterminable to the developers, let alone co-developers or others.

Avoid the Lasagna Architecture
The Lasagna Architecture is the outcome of a very strict layering approach wherein each layer only knows about the layer immediately below itself. Rather than actualizing the intended ‘perfect’ system, this approach often leads to an unnecessarily complex one.

Such a system is immensely complex to read, and making any changes to it is difficult. For even the slightest of change, the developer has to check most sections of the code, determine if the change in one layer would affect another, visualize the functioning of multiple layers, face unidentifiable errors in verification, and so on.

Avoid Abstractions and Dependencies
Abstraction is a process that envelopes a complex code block in a layer of simplicity. However, despite assigning a simple name to call the function, this method makes the overall process inherently more complex.

The function might have numerous interconnected parts, dependencies, and implementations of which the developer might be unaware at the time of calling. In fact, when abstractions aren’t dealt with properly, they ultimately lead to a lasagna architecture, resulting in the related issues and undesirable complexities.

Moreover, abstractions heighten the risks of improper or unnecessary coupling, which is a major deterrent to simplicity. The same applies to dependencies. Although dependencies are inevitable at times, it’s imperative to avoid them whenever possible.

Avoid Dead Code
A habit among developers is to include lines of codes that have no present purpose but are intended to be useful in the future. These are Dead Codes. By making systems unnecessarily complicated, they do more harm to the system than good.

Unless a line of code has any immediate purpose, it’s always advisable not to use it.

Avoid Flaunting
It’s often alluring for developers to flaunt their skills and to do things in ways unique to them, to make applications unnecessarily complicated. Although this might sound trivial in the context of this blog, it’s a significant factor deterring people from achieving the KISS principle in software development.

Conclusion
By emphasizing simpler coding and less interconnected parts in software systems, the KISS principle in software development represents a less is more mindset. This is a matter of habit and must be inculcated over time, both by the individual developer and the business as a whole. Leaving aside the prejudices plaguing this field, it’s high time that the software development industry, as a whole, educates itself and embraces the idea of keeping it simple. The result would be a win-win situation, beneficial to developers, businesses, and end-users.

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