DIY WordPress – World’s Shortest Plugin

(Reading time: 3 – 4 minutes)

This little article isn’t for everyone, but if you have ever wondered exactly what a WordPress plugin is, it’s for you. Also, I have an ulterior motive for this snappy little article, but you’ll have to wait for a couple of weeks to find out.

The short answer is this:

A WordPress plugin is it’s “Plugin name,” which must be in a file where WordPress can find it when WordPress scans for plugins.

As long as you have at least this, WordPress will activate and register your plugin:

1

<?php /* Plugin name: A Minimal Plugin */ ?>

One line, can’t get any shorter than this.

How WordPress plugins work

1. WordPress scans the plugin directory.
2. Files in the plugin directory are parsed for “Plugin name.”
3. Plugin state is stored in options table

Disclaimer: this is based on 1. common sense, and 2. cursory inspection of the WordPress source code. I’ll be doing more digging later into the scanning and parsing code.

Screencast!!!

Uh, no. Youtube is down. Can’t upload. Can’t link. Bummer. Maybe later.

See how easy that is? Here’s the script:

1. Introduction and explanation of minimal plugin. Why I always seem to have a cold when I make these screencasts is beyond me.
2. The plugin name is “A Minimal Plugin” and it’s located in wp-content/plugins/minimal.php. You’ll see the file name when we look at the active_plugins key in the options table in the WordPress database. In any case, we activate the plugin here.
3. After activating A Minimal Plugin, we take a look at the source code. It’s really just one line, but the WordPress editor reformats for display, something you need to know about if you take on any programming in WordPress. (It’s also intensely annoying and will screw up your escape codes.)
4. Next we examine the options.php page which lists out the keys and values for the options table in the WordPress database. The data containing plugin names is serialized, not shown in this display.
5. Lastly, a quick check of the active_plugins key using an SQL browser shows, indeed, that the minimal.php file name is stored.

In a couple of weeks, I’m going to show you why this is important when you’re building plugins for yourself. (Weekenders are going to get why you should consider building (or having your web team build) your own little plugins too.)

Your turn

Implement this plugin and take a screen shot, I’ll link the first three here:

1. First up is Ricky Buchanan, posting her screenshot example on Skitch. Very cool!
   
   

   Ricky's Minimal Plugin

2. Second isn’t bad… here’s Marshall’s:
   

   Marshall's Minimal Plugin

   Visit Marshall & family at Real Off Grid Living.

3. Third, could be worse.

Seriously, this takes about 5 minutes to do, and you will get something out of it. (deliberate practice)

Tagged as: DIY WordPress, Plugins