Questions and reusability

Reusability is a very good concept. If a function or module can be reused, the code becomes clearer, smaller, more modular, you don’t repeat yourself, and the solution feels nice.

Let’s start building questions. Our base question is: Is reusability good?

And we always ask: How should I modify this question to help my thinking?

”Is reusability good?”

Asking questions — and asking them in a better way — is important for clarifying our thinking.

We can ask: Is reusability good? This is a very basic question, and you’ll probably just answer yes or no. It doesn’t help you think.

Modify it a bit: Is reusability always good? Now the question is a little more nuanced, and you can sense that maybe it isn’t.

To make the question more scalable, change it with when: When is reusability good? This actually gets you thinking, and helps you find answers like “the code will be modular”, “I won’t repeat myself”, or “I can use the code in more places.” You start finding the advantages.

Now we have answers, and we have arguments in favor of reusability. That helps us understand it better.

Flipping the question

Okay, we understand reusability and we know how to use it. But we should also know when we need to use it and when we don’t. So how should we modify the question to help thinking?

Adding a negation always helps thinking about disadvantages: When is reusability not good?

Let’s take an example:

• When a screen is reusable and is used in 2 different places, reusability raises the number of test cases. You have to validate a single change across 2 different flows in 2 different places. The real question here is: what is the time we actually save? We gain some development time, but we lose testing time. Maintenance also takes more time and adds extra risk and complexity. So you may save some time and produce cleaner code — but you may lose more. In this case a copy can be the better choice.

Trading off

Now we have two questions that together clarify that reusability has both advantages and disadvantages. So we can make a tradeoff based on the answers and decide whether to make the code reusable or not.

Some important aspects to consider:

• Maintenance
• Scalability
• Testability and testing (not just unit tests — application testing as well)
• Reusability itself

Recap

• Better questions lead to better answers and better code.
• Reusability is a good and frequently used tool. In most cases it’s the right call — but like everything else, it has advantages and disadvantages. You just have to consider whether it’s worth it in your situation.

This post isn’t really about reusability. It’s about how to ask better architectural questions.