Since most applications can be represented by state machines, it is beneficial to make valid states in your program as clear as possible and invalid states impossible. This will enhance the readability, and maintainability of your code to everyone who sees it, including future you. In the rest of this article we will discuss one strategy for making invalid states impossible with an example in tsx and React. Replacing Booleans With Types Below you will find a tiny React component that displays fish from a fictional API.

Are you currently the only one on your engineering team who can read and understand your code? If you left for a new job, how often would your teammates need to call you in order to maintain the code you left them? Let’s talk about how to not get calls after you leave a job. Visual Hierarchies Visual hierarchies are a powerful tool. As readers they allow us to scan, giving us a sense of the main flow.

I want to tell you about an alternate design technique, it is called programming by intention. Rather than writing code that describes how to perform some action, you call a function. The interesting thing is the function doesn’t exist. Yet, we are going to call it as if someone wrote it ten minutes ago. We are going to follow a loop of call a function that doesn’t yet exist, implement what it does by calling more functions that don’t exist, until we have to implement the real code.

DRY is commonly interpreted to mean that code should not have duplicate structures. For instance two array indexes that both use rand(4) would be refactored away. Let’s look at an example of code that does exactly that. Person.new(names[rand(4)], jobs[rand(4)]) At some point, this is perceived as duplication and an abstraction is put in place. This abstraction is not logically consistent with the domain logic. Person.new(random_item(names), random_item(jobs)) At first this inconsistency is not inherently dangerous.

In the words of Jimmy Two Times, “I’m gonna go get the papers, get the papers.” The Don’t Repeat Yourself (DRY) Principle is commonly interpreted to mean, code with no duplicate statements. I’d like to explore that thinking with you for a few minutes so that I can demonstrate how it is flawed. I have written a small program that displays the name and job of randomly created people. Take a look at the :random_person function.