Duplication is better than Wrong Abstraction

Design Principle -- AHA

Prefer Duplication over Wrong Abstraction

In software development, engineers tend to create abstractions to make the code reusable and avoid duplication. It is good in most of the use cases but remembers, the product requirement is changing fast, if you create an abstraction at the very beginning, you are very likely to fall into a trap — The Wrong Abstraction.

If you keep working on the wrong abstraction, in the end, you will lose control of your codebase. No one can understand the codebase and you need a lot of documentation, comments, and diagrams to help you understand the existing behaviors. In order to reduce a few lines of code but create a wrong abstraction, it will make your code incomprehensible and unmaintainable.

Isn’t it Code as Documentation?

Imagine one of the use cases:

1. Engineer A sees a duplication in the codebase, he abstracts it

2. Time passes and new requirements come

3. Engineer B sees the new requirements almost fit the current abstraction and he adds one more parameter to determine the flow

4. Now, another requirement comes

5. Engineer C adds one more parameter to the code and introduces another condition to cater to the new requirement

public void doSomething(String param1, String param2) {
    // A...
    // B...
    // C...
    // D...
    // E...
}

public void doSomething(String param1, String param2, boolean flag) {
    // A...
    if (!flag) {
        // B...
    }
    // C...
    // D...
    // E...
}

public void doSomething(String param1, String param2, boolean flag, boolean flag2) {
    // A...
    if (!flag) {
        // B...
    }
    if (!flag2) {
        // C...
    }
    // D...
    // E...
}

Do you know what’s the problem here?

It is creating the Wrong Abstraction. People just want to reuse the code all the way but without considering the actual situation. In the end, they lose all code readability because of the wrong abstraction. It is so common in software development. Have you thought about this problem? How can you make it better?

If you face the situation, remember to go backward and create duplication. It helps readability and maintainability. Rethink how to create a better design when the requirement is stable enough.

Sandi Metz summarized this with a beautiful description:

prefer duplication over the wrong abstraction

This principle is also called AHA (Avoid Hasty Abstractions) which means keeping everything simple at the early stage even if it is duplicated.

Conclusion

To embrace code readability and maintainability, we should avoid hasty abstraction and make everything as simple as possible at the early stage even if using a naive approach.