I gave a talk on object-oriented programming with WordPress at WordCamp Miami 2019. This is the companion article that I wrote for it. If you’re just looking for the slides, click here.
You’re a WordPress developer who wants to use object-oriented programming in their next project. You’re already familiar with concepts like inheritance. The issue is that you’re not sure how to apply those concepts to design classes that feel useful.
This isn’t something to feel ashamed about! In fact, it’s a common problem when trying to use object-oriented programming with WordPress. It’s hard to know how to design classes that work well with WordPress. (That’s why this site has so many articles dedicated to that topic.)
But why is this so hard to do? Well, there are a few things going on. And together they create this situation that makes using object-oriented programming with WordPress complicated.
Continue reading How to approach object-oriented programming with WordPress
In a previous article, we saw how to design a class to represent a WordPress admin page. The article was an excellent resource for anyone looking to design a class to solve that specific type of problem. But it was only a starting point.
For example, we used the settings API to handle forms. But the settings API doesn’t quite do the job for every use cases. For those other cases, you’re going to need to manage the submission of a form yourself.
But to handle these different use cases, we’re going to need a more solid foundation. So we’re going to take the work that we did to design our admin page class, and we’re going to take it one step further. We’re going to design a whole system for WordPress admin pages.
Continue reading Designing a system: WordPress admin pages
As a WordPress developer, the topic of testing isn’t something that we hear about that often. And, if we do hear about it, it’s more often than not just one specific type of testing: unit testing. (That’s even the one that I’ve thought first!) In fact, it’s not uncommon to associate testing with unit testing because of this.
But software testing is an enormous field. There are a lot of different types of testing. While they might not all be as useful as unit testing, they still all serve a specific purpose.
That said, there are other types of testing that are as useful (or almost as useful!) as unit testing. Acceptance testing is one of them. It’s especially useful if you’re a plugin or theme developer.
Continue reading Introduction to WordPress acceptance testing
A lot of us have heard about unit testing. Out of all the different types of testing (and there are a few!), it’s probably the better-known one. It’s also the most common form of testing used with WordPress.
In the past, we’ve looked at how unit testing works with WordPress. That said, knowing how unit testing works is one thing. This knowledge doesn’t necessarily make it any easier to get started with it in your projects.
Some of us work with existing code bases. It could be a plugin, a theme or a whole WordPress site. How do you take the fundamentals of unit testing and apply them in that context?
This is a tricky question to answer, but it’s also an important one. Most of us will not start using unit testing in a vacuum. We’re going to start using it with one of those existing code bases.
This brings with it its own unique sets of challenges. It also means that you need to have a strategy for them. This will help make this transition smoother for you.
Continue reading How do you start unit testing existing WordPress code?
Do you ever take the time to read the code of your favourite PHP framework or library? If you have, there’s a good chance that you might have seen them use PHP’s reflection API. And, if you don’t read other people’s code, you should start doing it! (It’s a great learning tool.)
Now, let’s get back to the reflection API. This is an API that gets used quite a lot by framework and library developers. But the funny thing is that it’s almost never talked about when you’re looking at resources to learn PHP. (Or even advanced PHP resources for that matter.)
This is unfortunate. That’s because PHP’s reflection API serves a unique and important purpose. That’s why developers that build our frameworks and libraries use it so much.
Continue reading PHP reflection API fundamentals
Custom post types are one the most powerful features of WordPress. You can use them to save any type of data that you want in the
wp_posts table. Most plugins that build complex features on top of WordPress (e.g. WooCommerce) rely on them.
But custom post types aren’t just useful for developing new features on top of WordPress. They also allow us to rethink how we use object-oriented programming with WordPress. And, as we’ll see, this is an important step in your journey learning object-oriented programming with WordPress.
That’s because having a different view of custom post types will expand your object-oriented design horizons. They’ll help you build new types of classes that you might not have considered before. And this can be a game-changer when creating larger object-oriented plugins or themes.
Continue reading Designing entities using WordPress custom post types
In a previous article, we discussed how to design a class representing a WordPress admin page. This was important because almost every plugin or theme needs an admin page. But this isn’t the only common thing that plugins or themes add to the WordPress admin.
Another one of those is the meta box. If you’re not familiar with meta boxes, they’re the draggable boxes that you see on the post editing screen. It’s quite common for plugins and themes to add post-specific functionality through them.
This makes them a good topic to discuss with object-oriented programming. (Is there really a bad topic to discuss with object-oriented programming!?) And, as we’ll see, meta boxes have a lot of in common with admin pages. This means that designing a class to represent them will be a lot like what we did for admin pages.
Continue reading Designing a class to represent a WordPress meta box
I spoke at LoopConf 2018 on software complexity and how to manage it. This is the companion article that I wrote for it. If you’re just looking for the slides, click here. You can also find a recording of the talk here.
As developers, we spend a lot of time writing code. But we spend even more time maintaining that code. How often do we go back find that that code has become this tangled mess that we almost can’t understand? It’s probably more often than we want to admit!
We wonder, “How did this happen? How did this code get so messy?” Well, the most likely culprit is software complexity. Our code became so complex that it became hard to know what it did.
Now, software complexity isn’t a topic that developers are often familiar with when they start coding. We have other things to worry about. We’re trying to learn a new programming language or a new framework.
We don’t stop and think that software complexity could be making that job harder for us. But it is doing precisely that. We’re creating code that works, but that’s also hard to maintain and understand. That’s why we often come back and ask ourselves, “What was I thinking!? This makes no sense.”
That’s why learning about software complexity is important. It’ll help you increase the quality of your code so that these situations don’t happen as often. And this also has the added benefit of making your code less prone to bugs. (That’s a good thing even if debugging is a great learning tool!)
Continue reading What is software complexity and how can you manage it?
That means that this is still a great excuse to use object-oriented programming with WordPress. (Yay!) In fact, it’s an excellent opportunity to piece different object-oriented concepts together. This will let us design a system to extend the WordPress REST API!
Continue reading Designing a system: WordPress REST API endpoints
As you use object-oriented programming with WordPress more and more, you’re going to encounter new sets of problems. These problems aren’t as simple as the ones that you encountered when you started. But that’s also good news. It also means that you’re making progress.
One set of problems that you start to encounter as you advance in your use of object-oriented programming deal with scaling. As your code has more and more classes, it becomes a challenge to assemble these classes together. That’s why in the past we looked at how to design a class whose job was to do that.
But there are other problems that come with having a lot of classes in your code. It’s how much your classes depend on other classes. This is what we call coupling in programming. (Not just object-oriented programming.)
To help with coupling, a famous software engineer (Robert C. Martin who’s also known as Uncle Bob) created the dependency inversion principle. It helps you decouple your classes by making dependencies external to them. (There’s more to it than that. But this is one of the core elements of the dependency inversion principle.)
This reduces coupling but creates a new problem as well. That problem is that you can’t initialize objects inside your class anymore. You have to pass them to your own object through its constructor or some other method like a setter method.
This makes it even harder to assemble your classes together. This is why software engineers created dependency injection. It’s a programming technique that helps solve this problem.
Most web application frameworks use it in some form or another. But that’s not the case with WordPress since a lot of its code isn’t object-oriented. That said, if you want to build an object-oriented plugin for WordPress, it’s pretty much mandatory. Lucky for us, it’s not that hard to use dependency injection in your own code!
Continue reading Using dependency injection with WordPress