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If you have a function named get_post(), it will conflict with WordPress’ own get_post() function and result in a fatal error. That's not a good user experience. Writing good code means making sure that your code doesn't conflict with other developers' code. The best way to ensure that is to prefix or namespace all your classes, functions, and anything else within the global namespace.

Throughout most of WordPress’ existence, it has supported versions of PHP versions earlier than 5.3, which is the version of PHP that standardized namespaces. This meant that it was standard practice to use a faux namespace by prefixing classes and functions. Prefixes should be unique to the plugin. The WordPress coding standards recommend naming classes and functions using snake case. Therefore, a function named get_post() would become prefix_get_post(), and a class named Post would become Prefix_Post.

WordPress 5.2 changed its minimum PHP requirements to PHP 5.6. This means that plugin authors who want to support the same PHP versions as WordPress are no longer tied to the old practice of using prefixes. For this reason, it's probably best to look at other standards for naming, such as those outlined in the PHP‐FIG standards (https://www.php-fig.org).

For the purposes of this book, the recommendation for namespacing your code will be to use the built‐in method of namespacing in PHP. Namespaces allow you to group your code under a unique name so that it doesn't conflict with other developers' code. Using the “Super Duper Forums” plugin example, your namespace would be called SuperDuperForums.

Namespaces must be the first code, excluding the opening <?php tag and inline comments, in a PHP file. In the following example, see how a custom class named Setup is handled. Because it is under the SuperDuperForums namespace, there's no need to prefix it.

<?php namespace SuperDuperForums; class Setup { public function boot() {} }

Class and function names are not the only consideration when namespacing code. There are other times when you'll have things in the global namespace that might conflict with other plugins running in WordPress. Such cases may include storing options in the database (see Chapter 3, “Dashboard and Settings”) or loading a JavaScript file (see Chapter 6, “JavaScript”). In such cases, it's generally best practice to prefix option names with your plugin name, such as super_duper_forums_ option_name, and prefix script handles similarly, such as super‐duper‐forums‐ script‐name.

You may have noticed that the option name used snake case (underscores) and the script handled used kebab case (hyphenated) in the previous example. The difference in practice has arisen over the years and can be confusing to new plugin developers. In general, anything referred to as a handle is in kebab case, and everything else is in snake case. Often such differences are superficial and not overly important. When in doubt, stick with snake case, and you'll be alright.