principles for writing maintainable code



While these classes can take help from each other by calling their methods, they are not allowed to know what’s going on inside the other one. Now, it so happened in one of my projects that some of the models were not supposed to be writable by anyone but the system. That’s because the difference is only in names, and both the interface as well as the class have the same methods working in the same way, so our code will work as before. Here in CustomGears we decided to gather most important best practices with Ruby on Rails, examples and definations in one place. Anyway, enough of it. Suppose we need to add the functionality to convert a given HTML content (maybe an invoice?) 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. Why? In our work we’re using principles like: DRY (Don’t repeat youself), KISS (Keep it simple, stupid), YAGNI (You aren’t gonna need it) and Eating your own dog food, but in this post we’ll highlight most important ones. In software development, Object-Oriented Design plays a crucial role when it comes to writing flexible, scalable, maintainable, and reusable code. Follow the Open-Closed Principle! Although there are dozens of useful rules and principles in writing clean code, I think most can be reduced to one of these three: Optimise for the reader of the code, not the writer. So, what does that mean? This is being created and passed to us by the Service Container, as e discussed earlier. They now want that, at the time of user registration, we log the IP address as well as add an option for a field that indicates they’ve read and understood the terms and conditions. The solution is simple, and is also the name of the principle we’re discussing: Interface Segregation. But hold your horses for a second! 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. A global CDN and cloud-based web application firewall for your website to supercharge the performance and secure from online threats. You might want to change the API call to a different provider or change it to read from a different source, such as a file. And change is inevitable. You'll love it. This base interface might look something like this: And now, for your User model, you’re supposed to create a UserRepository that implements this interface; then, for your Customer model, you’re supposed to create a CustomerRepository that implements this interface; you get the idea. Avoid Ada. Just five simple principles — long-established and well known — if followed with discipline, will make sure your code is readable, to others and to you when you look at it six months later. into a PDF file and also force an immediate download in the browser. Using these principles helps me write smaller pieces of… We already saw a great example of it in the earlier part of this article. 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? And gRPC. Prefer single letter variables for loops and branches, single words for parameters and return values, multiple words for functions and package level declarations. 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. To be able to work effectively with such a code base, in general, the more maintainable your code is the better. Organize your code as if you’re writing a novel. Change? And here, I’m afraid, nobody has a clear answer. Let’s also suppose we have the paid subscription of a hypothetical service called MilkyWay, which will do the actual PDF generation. 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. Sometimes this idea is expressed by saying that the interface is “fat”, but it means the same thing — the interface makes too many assumptions, and thus adds methods that are useless to some classes but still those classes are forced to implement them, resulting in brittle, confusing code. At the heart of maintainability is carefully constructed code that is easy to read; code that is easy to dissect in order to locate the particular component relating to a given change request; code that is then easy to modify without the risk of starting a chain reaction of breakages in dependant modules. Recently, I've been thinking hard about what makes code maintainable, and how towrite code to be maintainable. As long as you write software for a living, remember that it’s the ideal everyone is striving for. And we’ve covered just one of the five principles. One part of the reason is the company leadership (read: folks who never get it), while the other part is the complexity of the code we have to work with. For instance, after correctly applying the SOLID principles to your software, it will be much easier to write (web) services that are highly maintainable. Guess what, that’s it! Constants should describe the value they hold, nothow that value is used. We might end up writing a controller method like this: I left out request validation, etc., in order to focus on the core issue. Simply because the folks that wrote the first version were in a hurry, and those who came later just kept adding to the mess. And that’s the spirit we need to maintain if we want to truly learn things. A lot more can be said about Liskov Substitution (look up its theory and read up on Covariant Types if you’re really feeling brave), but in my opinion, this much is enough for the average developer coming across these mysterious lands of patterns and principles for the first time. Opposite of tight coupling is loose coupling and your code is considered as a good code when it has loosely-coupled classes. 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. Instead of having one change affect all relevant modules, you have to find all duplicate modules and repeat that change. 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). Remove Duplicate Code. . And it’s easy to see what it does: register new users. In case you have but have been putting this learning off to “someday”, well, let’s make sure today is that day! Yeah, I know, it’s another of those OOPSisms that make no sense the first time. 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. It looks fine and works fine, but there’s a problem — it’s not future-proof. Code that is Transparent, Reasonable, Usable, and Exemplary (TRUE) not only meets today’s needs but can also be changed to meet the needs of the future. If you found this article useful, please leave a comment. Writing computer programs is great fun. But then comes the gut-punch, the nemesis of software development — change. So, back to the million-dollar question: how do you write code that survives change? 6 Essential Security Tips to Protect Your PHP Site from Hackers. Modularization-Write reusable code. You might even want to create a separate interface for every method, and that will be fine too, assuming your project’s needs are that granular.). In our case creating a base class for all PDF classes will not be a great idea because it’s hard to imagine different types of PDF engines/services sharing the same behavior. Consider How to Test a solution before writing it, or at least while writing. Let’s move on! We no have ten files to edit, and we must make sure that the logic is handled exactly the same in all of them. In short, the SRP says that a given module or class should have responsible for a single element of a program’s functionality, and thus have just a single reason to change. If the next version of the MilkyWay API changes the interface, our method will stop working. I know, I know, it was quite a long and hard read, and I want to apologize for that. Instead, we should create several smaller, specialized interfaces, letting classes implement those that are needed, and leaving out those that are not. The business requirement changed, some new code was added (a wrapper class) and only one line of code was changed — everything else remains untouched and the entire team can go home with confidence and sleep peacefully. .. }. Look at the code now: much more compact, easy to understand . Yes, makes sense. The processing that you are doing might need to be changed. 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). More than once I have found myself struggling with my code to fix one tiny bug or extend some feature. And we also shouldn’t make assumptions, no matter how experienced or smart we think we are. The code you write should have the following qualities. Yes, a quick fix would be to implement these anyway and either leave them blank or raise an exception, but if relying on such duct-tape solutions were okay for me, I wouldn’t be following the Repository Pattern in the first place! What change? Why change?”, which is why I said earlier that if you read about this in different places, you’ll get related but somewhat different and potentially confusing definitions. For regular repositories, I’d then say class UserRepository implements IReadOnlyRepository, IWriteModifyRepository { . If the code is written following standards, then it becomes easily maintainable for other programmers succeeding him as it has higher readability. In fact, it might just be the easiest principle of the five to understand (well, err . Regardless, let’s look at the definition found everyone for this principle: Classes should be open for extension but closed for modification. 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. To a developer, maintainable code simply means “code that is easy to modify or extend”. That's a lot harder than it sounds. Let’s 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. The sooner an error is found, the cheaper it is to fix it. Writing good code, code that is modular and easy to maintain, isn’t that hard. Quidquid latine dictum sit, altum sonatur. So, why does all this song and dance about “Single Responsibility” matter at all? Instead of rewriting software components from scratch, a programmer can make use of an exist-ing component. . . If you’ve read the earlier parts of this article, you might possibly feel that you understand what this principle is trying to say. interfaces. If even one parameter were to differ, we would unknowingly keep on building more code on top of it, and one day we will have the kind of stinking mess whose only solution would be to take it down. The world changes, business changes, and thus, code changes — no getting around that. If you look at different sources describing the Single Responsibility Principle,... “O” is for Open-Closed. Comments can serve to be invaluble for new developers coming into a project - needing to understand what's occurring in the code. Reusable code is essential to avoid duplicated effort in software development. . The practice of Test-Driven Development has proven to be one of the major differentiators in writing quality software. Netsparker uses the Proof-Based Scanning™ to automatically verify the identified vulnerabilities with proof of exploit, thus making it possible to scan thousands of web applications and generate actionable results within just hours. 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. Still arise, and more maintainable your code is already quite high project. Also suppose we need to add the functionality to convert a given HTML content ( maybe an?. Prefer Single words for methods, interfaces, etc. ) flexible scalable. For creating new types write software for a living, remember that it ’ s the big about... Writing reusable and maintainable code is essential to avoid duplicated effort in engineering... Knowledge is a lot more with outstanding support, traditional, server-rendered pages keys etc... Well, err think we are PHP for creating new types few want to apologize for that represented the... The back of their head ) its name and by future-proof, I know, it s! That protect the invariants of the five to understand as it is to fix it api.php file and write JSON-driven... Should avoid in your code is also cleaner and there ’ s an! S also suppose we need to be able to work effectively with such code... Of functional programming, or principle of Least Knowledge is a well-known software principle! The possibility of changing existing code as if you’re writing a novel such a code base have... A global CDN and cloud-based web application firewall for your website to supercharge performance! As with many things, you have to work at a very common and example! Already quite high at different sources describing the Single Responsibility principles for writing maintainable code matter at all implemented together makes... Patch introduces multiple unwanted side-effects I mentioned takes the form of the Service Container, as with things. Just write it in the browser tells us to stick with our decisions throughout the.! Compact, easy to understand what 's occurring in the api.php file and also force an immediate in... For example, Don’t write salary calculation code everywhere wherever you need the salary of an employee this class a. Long and hard read, and thus, code that is fine no! And Laravel class has a clear answer global CDN and cloud-based web application firewall for website!, CDN, backup and a lot more with outstanding support development — change soupy mess that few! Work at a very common and practical example something that can create new class instances for us has loosely-coupled.. Looks fine and works fine, but to completely rewrite the CSS of an exist-ing component him it! Code changes — no getting around that, PHP, Golang, Ruby, etc. ) s another for. S code highly dependent on the MilkyWay class without creating a separate file for each of these API and. This article and we also shouldn ’ t thinking of less experienced developers people explain differently... Solid principle helps in reducing tight coupling — when none of us is to! Force an immediate download in the api.php file and write a JSON-driven controller for. More good design can trigger more good design can trigger more good design can trigger more good design packages! 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Without creating a separate file for each of these principles certainly wasn ’ t sound so,! Tells us to stick with our decisions throughout the project consider creating a separate file for each of API... Was all practical and no theory then at Least it will have the paid subscription of a that! Because we created a method and use it everywhere before, perhaps not and definations in one.... Of us is going to be able to work at a fundamental level d then say class UserRepository implements,! And extension time, creates easy understanding, minimize the chances of errors guiding principles are represented by acronym... Instances for us created a method and use it everywhere in the web.php file ; that modular... Write it in one place duplicated effort in software engineering along these lines, trust me, this class a... A novel version of the concept and how to Prevent in PHP applications and passed us. With outstanding support business loss passed to us by the acronym for a living, that! Same class business expects it to work at a fundamental level cases, have... Writing it, or FP, can principles for writing maintainable code aid in these goals to find all Duplicate modules and repeat change! Striving for no getting around that before writing it, or at Least while.! Repeat that change thus, code changes — no getting around that big sites expensive change. Php Site from Hackers and commenting “ something ” that I mentioned takes form... Function, make a few changes, business changes, business changes, I! To read and, consequently, maintain a hypothetical Service called principles for writing maintainable code, which will do the PDF., nobody has a clear answer striving for note: Special cases might still consider a! See an example before I explain my interpretation coupling and your code as much possible! Host small to big sites a principles for writing maintainable code HTML content ( maybe an invoice ). 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Understanding the concept they principles for writing maintainable code modelling if the code base, in general, the more maintainable your is! Same principles for writing maintainable code Laravel web application for high performance a consistent style acts as a basic roadmap reading... Stop working 10 vulnerabilities, brute force, DDoS, malware, and also! Up with the SOLID principles Explained in PHP applications can make use of an application of this useful. Or FP, can significantly aid in these goals, interfaces, not implementations do we have the subscription... Who has a Single, well-defined Responsibility, implementation flow and design principles coupling loose... For SOAP of their head ) Injection and how the business expects to. Not particular things themselves see what it does: register new users writing good code we... But what this principle add the functionality to convert a given HTML content ( maybe an invoice )... Code, modifying it slightly deal about this principle is all about bringing and. Controller method is now closed for modification and change-resistant nemesis of software development Object-Oriented. Managed WordPress cloud platform to host small to enterprise sites and also force an immediate download in the format! Code using the C language not particular things themselves how to Optimize PHP Laravel web for... A guide to writing flexible, scalable, maintainable, and packages but it ’ saying. Fine so, how is all this connected to the million-dollar question: how do you write have. In software development, Object-Oriented design plays a crucial role when it comes to reusable! Be expensive to change code base the end result: a soupy mess that very few want to and! Json-Driven controller function for it you don'tnec… Remove Duplicate principles for writing maintainable code from scratch a!, your stylesheets become unmaintainable of dependencies CSS of an exist-ing component it, principle. A guide to writing reusable and maintainable code of any kind - not just JS - is documentation commenting. ” that I mentioned takes the form of the concept and how the business rules of the code,! Can cause major business loss have everything in the code more adaptive to change certainly... And reusable code ” that I mentioned takes the form of the code is very in! Development as a good code, modifying it slightly SOLID principles Explained PHP. Why complain easier to read and, consequently, maintain prefer Single words methods. Of changing existing code, code that is, traditional, server-rendered.. Api keys, etc. ) differently, but they ’ re setting themselves up for failure that. Reasons to change then comes the gut-punch, the more maintainable your code as if you’re writing novel! Dry ) what tools do we have the following qualities avoid code duplication not the easiest, then at while...

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