Drupal Themable Functions - Where the Fun Really Begins

Drupal includes these groovy things called theme-able functions. A function is a bit of PHP that does something - like generate the output of the breadcrumbs or menu links.

When a function in Drupal is theme-able, it means we can override the default function and modify the output of it. Now that is where the fun really begins!

Over the next 6 months or so (yes, really, 6 months) I'm going to attempt to post about every single theme-able function in Drupal 6 (there's a lot), and show you a simple modification to each one.

First, lets have a look at these functions, surely the first thing we want to know is which of all the functions in Drupal are theme-able, right?

Thank-fully the good people over at Drupal made it real easy to find them all in one place - http://api.drupal.org/api/group/themeable.

There's some excellent information about theme-able functions on that page, so be sure to visit it and read up.

Now, you'll notice that all the core theme-able functions begin with theme_ which is great as its another sign that the function can be themed. Its also the first thing we change when over riding the function, for example...

function theme_xml_icon($url) {
// normal code here...

... becomes,

function mytheme_xml_icon($url) {
//normal code here...

Where "mytheme_" is the name of your theme.

Ok, so enough of the overview, lets get down to business! Just for the record, I've decided to work in reverse alphabetical order (more so I can actually remember what I've covered), but if you have a special request let me know:), so that means its the xml icon function up first, and that I will attack in the next lesson.

Last updated 7th August, 2008 - 3:22am

Authored by Jeff Burnz on