A Step-by-Step Guide to Developing a WordPress Plugin

TL;DR: This article provides a comprehensive walk-through of how to develop a WordPress plugin. Using the “Design Patterns in WordPress” plugin as a demonstration, we’ll take a deep dive into the construction of the plugin and explain the use of design patterns in a WordPress context. From setting up your PHP files to implementing a singleton pattern, this guide will help you understand the essentials of WordPress plugin development.


WordPress, being a versatile platform, offers numerous opportunities for developers to customize and extend its capabilities through plugins. These plugins add new features or functionalities to a WordPress website. However, creating a plugin might seem daunting to those new to it. In this article, we aim to demystify the process of WordPress plugin development by guiding you through the creation of a simple yet useful plugin – “Design Patterns in WordPress”.

Setting Up the Base Plugin File

The first step in creating a WordPress plugin is to set up the base PHP file. This file contains the essential metadata for the plugin and initiates its functionality.

phpCopy code/*
* @license GPL-2.0+
* @link http://www.jamesportis.com
* @copyright 2016 James Portis
* @wordpress-plugin
* Plugin Name: Design Patterns in WordPress
* Plugin URI: http://www.jamesportis.com
* Description: An example WordPress plugin used to demonstrate two design patterns in the context of WordPress.
* Version: 1.0.0
* Author: James Portis
* Author URI: http://www.jamesportis.com
* License: GPL-2.0+
* License URI: http://www.gnu.org/licenses/gpl-2.0.txt

if ( ! defined( 'WPINC' ) ) {

include_once( 'class-design-patterns-wordpress.php' );


This PHP script starts with a documentation block containing the metadata of the plugin. The if statement following the comments checks if the WPINC constant is defined. If not, the script execution is terminated. This is a best practice for working with WordPress installations to prevent direct file access. After that, we include our plugin class and call for the static get_instance function on the Design_Patterns_WordPress class.

Developing the Plugin Class

In the second step, we develop the main class for our WordPress plugin. This is where the core functionalities are defined.

phpCopy code/*
* @license GPL-2.0+
* @link http://www.jamesportis.com
* @copyright 2016 James Portis

class Design_Patterns_WordPress {

private static $instance;

private function __construct() {
// Set up the necessary data to get the object going

public static function get_instance() {
if ( null == self::$instance ) {
self::$instance = new self;
return self::$instance;

The class Design_Patterns_WordPress is where the action happens. We define a private static variable $instance inside the class. It is private so that no outside modules can use it, and it is static so that the instance to which the variable refers is shared across all objects.

Next, we define a private constructor where we set up the necessary data for the object. The constructor is private to ensure it can only be invoked within the class itself.

The get_instance method, which is marked as static, is used to return an instance of the class and create a new one if it doesn’t already exist. This method is at the heart of the Singleton design pattern and is used to maintain a single instance of the class. If $instance is null, a new instance of the class is created and assigned to $instance. Finally, a reference to $instance is returned.


Developing a WordPress plugin is a rewarding endeavor that enables you to extend the platform’s functionality according to your specific needs. This walk-through of the development of the “Design Patterns in WordPress” plugin provides an understanding of the essential steps in the process. By incorporating best practices and design patterns such as the Singleton pattern, we can create efficient and secure plugins. Remember, the journey of WordPress plugin development is filled with continuous learning and exploration. So, get started and keep experimenting!