Best Practices

Here are some best practices to help organize your code so it works well alongside WordPress core and other WordPress plugins.

Avoid Naming Collisions Avoid Naming Collisions

A naming collision happens when your plugin is using the same name for a variable, function or a class as another plugin.

Luckily, you can avoid naming collisions by using the methods below.

Procedural Procedural

By default, all variables, functions and classes are defined in the global namespace, which means that it is possible for your plugin to override variables, functions and classes set by another plugin and vice-versa. Variables that are defined inside of functions or classes are not affected by this.

Prefix Everything Prefix Everything

All variables, functions and classes should be prefixed with a unique identifier. Prefixes prevent other plugins from overwriting your variables and accidentally calling your functions and classes. It will also prevent you from doing the same.

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Check for Existing Implementations Check for Existing Implementations

PHP provides a number of functions to verify existence of variables, functions, classes and constants. All of these will return true if the entity exists.

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Example Example

//Create a function called "wporg_init" if it doesn't already exist
if ( !function_exists( 'wporg_init' ) ) {
    function wporg_init() {
        register_setting( 'wporg_settings', 'wporg_option_foo' );
    }
}

//Create a function called "wporg_get_foo" if it doesn't already exist
if ( !function_exists( 'wporg_get_foo' ) ) {
    function wporg_get_foo() {
        return get_option( 'wporg_option_foo' );
    }
}

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OOP OOP

An easier way to tackle the naming collision problem is to use a class for the code of your plugin.

You will still need to take care of checking whether the name of the class you want is already taken but the rest will be taken care of by PHP.

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Example Example

if ( !class_exists( 'WPOrg_Plugin' ) ) {
    class WPOrg_Plugin
    {
        public static function init() {
            register_setting( 'wporg_settings', 'wporg_option_foo' );
        }

        public static function get_foo() {
            return get_option( 'wporg_option_foo' );
        }
    }

    WPOrg_Plugin::init();
    WPOrg_Plugin::get_foo();
}

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File Organization File Organization

The root level of your plugin directory should contain your plugin-name.php file and, optionally, your uninstall.php file. All other files should be organized into sub folders whenever possible.

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Folder Structure Folder Structure

A clear folder structure helps you and others working on your plugin keep similar files together.

Here’s a sample folder structure for reference:

/plugin-name
     plugin-name.php
     uninstall.php
     /languages
     /includes
     /admin
          /js
          /css
          /images
     /public
          /js
          /css
          /images

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Plugin Architecture Plugin Architecture

The architecture, or code organization, you choose for your plugin will likely depend on the size of your plugin.

For small, single-purpose plugins that have limited interaction with WordPress core, themes or other plugins, there’s little benefit in engineering complex classes; unless you know the plugin is going to expand greatly later on.

For large plugins with lots of code, start off with classes in mind. Separate style and scripts files, and even build-related files. This will help code organization and long-term maintenance of the plugin.

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Conditional Loading Conditional Loading

It’s helpful to separate your admin code from the public code. Use the conditional is_admin().

For example:

if ( is_admin() ) {
    // we are in admin mode
    require_once( dirname( __FILE__ ) . '/admin/plugin-name-admin.php' );
}

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Architecture Patterns Architecture Patterns

While there are a number of possible architecture patterns, they can broadly be grouped into three variations:

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Architecture Patterns Explained Architecture Patterns Explained

Specific implementations of the more complex of the above code organizations have already been written up as tutorials and slides:

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Boilerplate Starting Points Boilerplate Starting Points

Instead of starting from scratch for each new plugin you write, you may want to start with a boilerplate. One advantage of using a boilerplate is to have consistency among your own plugins. Boilerplates also make it easier for other people to contribute to your code if you use a boilerplate they are already familiar with.

These also serve as further examples of different yet comparable architectures.

  • WordPress Plugin Boilerplate: A foundation for WordPress Plugin Development that aims to provide a clear and consistent guide for building your plugins.
  • WordPress Plugin Bootstrap: Basic bootstrap to develop WordPress plugins using Grunt, Compass, GIT, and SVN.
  • WP Skeleton Plugin: Skeleton plugin that focuses on unit tests and use of composer for development.
  • WP CLI Scaffold: The Scaffold command of WP CLI creates a skeleton plugin with options such as CI configuration files

Of course, you could take different aspects of these and others to create your own custom boilerplate.