WordPress Object-oriented plugin skeleton

A quick OOP pattern / skeleton for creating WordPress plugins.

<?php
/*
Plugin Name: Your Plugin
Plugin URI: https://wordpress.org/plugins/your-plugin
Description: Your plugin skeleton
Version: 1.0
Author: you
Author URI: http://your-site.com
License: GPL2
*/

/* The class encapsulates the plugin and its functions */
class Your_Plugin
{
    /* Put any plugin variables here */
    var $plugin_variable;

    /* The constructor will be used to setup actions and filters */
    function __construct()
    {
        /**
         * Set a plugin variable
         */
        $this->plugin_variable = 'test';

        /**
         * Hook on plugins_loaded. This is the first hook available to regular plugins.
         * It happens when all plugins have been initialized and is the best place to put your logic.
         */
        add_action('plugins_loaded', array($this, 'plugin_loaded'));

        /* Optionally, add additional hooks here. */
    }

    /**
     * Put your main plugin logic here!
     */
    function plugin_loaded()
    {
        /* Here is how to call a function inside your class: */
        $sum = $this->add(1,2);
    }

    /**
     * A plugin function that adds
     * two numbers together and
     * returns them.
     *
     * @param $var1
     * @param $var2
     * @return mixed
     */
    function add($var1, $var2)
    {
        return $var1+$var2;
    }
}

/* This initiates your plugin */
$your_plugin = new Your_Plugin();

Interfacing with your plugin

Interfacing with your plugin is possible by either calling the global you created (last line), like this:

global $your_plugin;
$sum = $your_plugin->add(1,2);

If you hooked on plugins_loaded, this can be done pretty much anywhere – other plugins, themes, you name it!

Another popular pattern is creating a global function helper inside your plugin.

/**
 * Here is how to create a global function
 * for your plugin.
 */
function your_plugin_add($var1, $var2)
{
    global $your_plugin;
    return $your_plugin->add($var1,  $var2);
}

And here is how you would call the global function in that case:

/**
 * Here is how to call the external function:
 */
$sum = your_plugin_add(1,2);