principles for writing maintainable code
But what this principle does mean is that we restrict the possibility of changing existing code as much as possible. In this case, we can take advantage of a practice that goes something like this — program to interfaces, not implementations. If you look at different sources describing the Single Responsibility Principle,... âOâ is for Open-Closed. Yes, there are more interfaces now, and some might say there’s too much to remember or that the class declaration now is too long (or looks ugly), etc., but look at what we have gained: specialized, small-sized, self-contained interfaces that can be combined as needed and won’t get in each other’s way. This is a guide to writing reusable and maintainable code using the C language. All we now need to do is write a new IPDFGenerator wrapper class for SilkyWay and change the binding in our Service Container code: Nothing else needs to change, because our application is written according to an interface (the IPDFGenerator interface) instead of a concrete class. When writing code, there are many specific principles that aim to make your code more maintainable: DRY, the single responsibility principle, the Law of Demeter, the open/closed principle, etc.These are great principles to follow, but it can be difficult to keep all of them in your head at once. However, in simpler terms, it boils down to this: Each class in your codebase should have a very specific role; that is, it should be responsible for nothing more than a single goal. What about a client who has a legacy system running on the XML format? We already saw a great example of it in the earlier part of this article. The tables have turned, and that’s why we call this an inversion of dependencies. . Maintainable code is unit (and functional/integration if needed) tested so that if a change is made that introduces a knock-on effect, it's caught quickly and early, before the code's even checked in. When a Laravel application receives a web request, the URL is matched against the routes you’ve defined in web.php and api.php, and if there’s a match, the request data reaches the controller. Recently, I've been thinking hard about what makes code maintainable, and how towrite code to be maintainable. I must say that whoever came up with the definitions of these principles certainly wasn’t thinking of less experienced developers. Applications always change, and writing maintainable code is very important in software engineering. Because it greatly increases the chance of making a mistake and is a burden on the business (developer time spent on sorting out the mess). In extreme cases, developers have no other choice, but to completely rewrite the CSS of an application. In our case, we need to free ourselves from having to depend on the MilkyWay class, and instead depend on a generic, a type of PDF class (it will all become clear in a second). Those principles of OOP consist of: Second one is LoD, or The Law of Demeter: The code you write should have the following qualities. All this waste because we created a method that was not closed to change. . What change? We might end up writing a controller method like this: I left out request validation, etc., in order to focus on the core issue. In the example we discussed, I might have created two interfaces instead of one: IReadOnlyRespository (containing the functions getOne() and getAll()), and IWriteModifyRepository (containing the rest of the functions). Writing maintainable code Unless you write prototypes or applications that never make it past release 1, youâll soon find yourself maintaining and extending existing code bases. Suppose we need to add the functionality to convert a given HTML content (maybe an invoice?) The same is the case with the Open-Closed Principle, and the ones to come are a step ahead in weirdness. Probably the best managed WordPress cloud platform to host small to enterprise sites. Let’s also suppose we have the paid subscription of a hypothetical service called MilkyWay, which will do the actual PDF generation. Iâve decided to include a list of some valuable resources which can help you become better at both writing maintainable code and maintaining existing code that you didnât write. You can tell that the function is meant for routes defined in the web.php file; that is, traditional, server-rendered pages. It’s time for something serious: if you’re like me, you’re probably wondering, “Okay, all good. Reusable code is essential to avoid duplicated effort in software development. — when none of us is going to be authoring libraries. Once you get to this point, your stylesheets become unmaintainable. And you’d be right, in the sense that this principle is more or less a repetition of what we’ve discussed till now. If all the five SOLID principles were investment vehicles, this one would deliver the most long-term value in learning to code well (okay, I realize I say that about every principle, but you know, you get the idea). The practice of Test-Driven Development has proven to be one of the major differentiators in writing quality software. (Side note: Special cases might still arise, and that is fine because no design is perfect. In the Service Container in our example, we can write something like this: This is basically saying, anytime someone asks for an IPDFGenerator, hand them the MilkyWayPDFGenerator class. Unlike other resources found on the web that provide examples that you do understand but then leave you wondering how they’d help you in real-world cases, let’s dive into something specific, a coding style we see over and over, and perhaps even write in our Laravel applications. Practice Consistency tells us to stick with our decisions throughout the project. A naïve approach might be to have everything in the same class. When I came across this the first time, the definition I was presented with was, “There should be one, and only one reason for a class to change”. Prefer single letter variables for loops and branches, single words for parameters and return values, multiple words for functions and package level declarations. What do you do? Using these principles helps me write smaller pieces ofâ¦ Regardless, let’s look at the definition found everyone for this principle: Classes should be open for extension but closed for modification. Then, I learned the SOLID principles. If we were to take this logic out of the function and put it in a separate class, we’d now have two classes, each with a single responsibility to handle. But how is it even possible to dream of code that doesn’t change when all we’re doing as developers is chasing the coattails of change all the time? General Principles. The answer is that the controller method that looks so harmless is actually doing a number of different things: it’s validating the incoming request, it’s handling redirects, and it’s creating new users. So, what’s the big deal about this principle? 6 Essential Security Tips to Protect Your PHP Site from Hackers. However, as with many things, you don'tnecâ¦ Suppose now, that your client/employer’s needs have changed. Avoid Ada. How to Optimize PHP Laravel Web Application for High Performance? If what you've written in the past doesn't suit your needs today, it can be expensive to change. This is what I meant by focus and discipline: focus in code (one thing doing one thing only) and discipline by the developer (not falling for short-term solutions). Trust me, this principle is as easy to understand as it is intimidating in its name. All in all, our high-level class, which was earlier in control of creating lower-level class instances, now has to look to something else. It looks fine and works fine, but there’s a problem — it’s not future-proof. Refuse to use Ada. If you found this article useful, please leave a comment. If you have ever inherited bad CSS with the obligation of maintaining it, you might have felt some empathy towards others who would maintain your code in the future. Stripped of highfalutin jargon and distilled down to its most basic form, the principle of Interface Segregation has this to say: The more numerous, more specialized interfaces there are in your application, the more modular and less weird your code will be. We no have ten files to edit, and we must make sure that the logic is handled exactly the same in all of them. Now, while we can do absolutely nothing about the former, we can do a lot about the latter. And if we wish to use some other service someday, we’ll have to literally do a global search in our code editor and change all the code snippets that mention MilkyWay. What is SQL Injection and How to Prevent in PHP Applications? Suppose tomorrow we feel that the MilkyWay service is too expensive (or, as it often happens, their customer support has become shitty); as a result, we tried out another service called SilkyWay and want to move to it. In addition, reusable code helps performance by making it possible to Interface Segregation . Well, in simpler terms, that’s all this principle is saying: make sure your subclasses implement all the methods exactly as required, with the same number and type of arguments, and the same return type. Look at the code now: much more compact, easy to understand . A consistent style acts as a basic roadmap for reading code. The principles of functional programming, or FP, can significantly aid in these goals. In case you have but have been putting this learning off to “someday”, well, let’s make sure today is that day! So, how is all this connected to the Open-Closed Principle and Laravel? This “something” that I mentioned takes the form of the Service Container in the Laravel world. In Object-Oriented Programming, several techniques have been discovered and refined to achieve this goal, right from these SOLID principles we are studying to common design patterns, enterprise patterns, architectural patterns, and whatnot. Free SSL, CDN, backup and a lot more with outstanding support. But what it’s saying is that our code should depend on types of things, and not particular things themselves. Writing good code, code that is modular and easy to maintain, isn’t that hard. If you used a PDF-generation service and your code was littered with new ABCService() class, the day the business decided to use some other service would be the day remembered forever — for all the wrong reasons! With that understood, let’s create an interface that specifies which methods we want all of our PDF engine classes to contain: Through this interface, we’re saying that we expect all our PDF classes to have at least those three methods. Letâs take an example: Imagine that you write a program that calls an external REST API endpoint, does some kind of processing with the received data and writes it to a CSV file. You'll love it. Eh?? But my heart goes out to the average developer who’s been doing things intuitively (or the way they were taught to him) and can make neither head nor tail of the SOLID principles. Before you start rolling your eyes, consider that logging or maintaining an audit trail is a good, real-world example of such “read-only” models. Prefer single words for methods, interfaces, and packages.
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