101 Introduction to WP Plugins

Hi, my name is Philip King, welcome to this tutorial series on Writing a WordPress Plugin.

Viewing Order

Since each of the tutorials in this series builds on each other, I recommended you progress through the tutorials in the order they are presented.

Contents

Acknowledgements – Thanks

Before I begin I would like to thank Ronald Huereca at Devlounge for the article he wrote in 2007, which prompted me to produce this series.
I would also like to thank all those at WordPress for producing such a brilliant and free application.

 Outline – Overview

In the last few years the powerful open source WordPress software has become very popular, not just for basic blogs but for full blown web environments. This has been made possible to a large part by the extensibility provided by the WordPress Plugin API interface.
In this series we’ll take a look at exactly what it takes to build plugins for WordPress.
The content of the series begins with this introduction and covers everything you need to write a plugin for WordPress 3v0 and above.
Topics included are, basic plugin construction, hooks, action, filters, building admin and user panels plus the use of JavaScript, CSS and AJAX in your plugins.
We finish with some tips on releasing your plugin to the WordPress community and discuss how to get free plugin hosting and publicity from WordPress.

Home of WordPress

As all WordPress users know, plugins are essential for adding additional functionality to your WordPress based website.
Plugins can extend WordPress to do almost anything you can imagine.
If you don’t already have WordPress, a copy can be downloaded, free of charge, from WordPress.org
On the WordPress site, if you click on the Extend menu item and select Plugins from the dropdown menu you will be taken to the WordPress Plugin Directory.

Available WordPress Plugins

The plugin page shows the currently featured WordPress plugins as well as popular categories of plugin.
As you will see, plugins come in all shapes and sizes, there is a plugin to do just about anything in WordPress.
By now you might be asking yourself, “why am I being shown this, I want to know how to write a plugin”.
Well the answer to that query is simple, when you begin writing a plugin, the best place to start is by extending an existing plugin if at all possible.
For example, if you wanted a plugin to show Google Maps on your website you would begin your plugin research by doing a Google Maps search in the WordPress Plugin Directory.
Then select the plugin most closely related to the plugin you intent to write and modify or extend as necessary.
One of the really nice features I like about the WordPress environment is the fact that all the source code is available for you to play with.

Who is This Tutorial For?

Ok, lets get back on topic, writing a plugin for WordPress. Who is this tutorial for?
This series of tutorials will start off very introductory and will assume your knowledge of writing plugins is zero.
This series of tutorials will benefit those interested in writing their own plugin from scratch, those that like to tinker with plugin code and theme designers.
I will presume you know your way around the WordPress websites interface.

You will need:

• A beginners to intermediate knowledge of PHP, JavaScript and CSS

These tutorials do assume you are already familiar with the basic functionality of WordPress, and PHP programming.

Tools for the Job

To write WordPress plugins you will need a programming environment to help you with the php coding. There are lots of applications out there and if you have a preference then just go a head and use them. The tools I use are:

• The Notepad++ text editor as it is quick and simple, covers a wide range of programming languages and has excellent code highlighting and formatting.

  http://notepad-plus-plus.org/

• The PDT Eclipse IDE because it’s open source and has plugins for editing not just PHP but Javascript etc. and has a very good code completion facility. As you would expect, the downside is the learning curve, it does take some time and effort to learn.

  http://eclipse.org/pdt/downloads/

• My browser of choise is Mozilla Firefox.

  http://www.mozilla.org/

• Now although you can use your live website, I recommend you use a local installation of WordPress for your development. I would recommend WAMP Server for Windows users and MAMP Server for Mac users.
  http://www.wampserver.com/en/

  http://www.mamp.info/en/.

If you need a tutorial on setting up a local development server for Windows, you can find one on my website, under the title, “Installing a Local Development Server (Video)”.

http://kingsolutions.org.uk/wordpress/wordpress/installing-a-local-development-server/

If you need a tutorial on installing WordPress on a Local development server, you can find this on my website under the title, “Installing WordPress in a Local Development Environment (Video)”.

http://kingsolutions.org.uk/wordpress/wordpress/installing-wordpress-in-a-local-development-environment/

For this tutorial series I will presume you have WordPress 3 or better installed.

Conclusion – Summary

Well, that’s all for this introduction, see you in the next lesson where we will discuss the structure of plugin coding.