Drupal 7 Module Development

A module's hook_theme implementation just needs to return an array of theme
hooks it is creating. For example:
/**
* Implements hook_theme().
*/
function retro_theme() {
return array(
// The array key is the name of the theme hook.
'wonder' => array(
// Use a template and give the template's name.
'template' => 'wonder',
}
// Specify the default variable names and their values.
'variables' => array(
'twin' => 'zen',
'with_monkey' => FALSE,
'activations' => array(),
),
// Add a partial pattern to help hook theme suggestion
// matches.
'pattern' => 'wonder__',
),
'austinite' => array(
// Specify the name of the render element.
'render element' => 'my_element',
// We don't use this theme function often, so let's put
// it in a separate file that is lazy loaded, if needed.
'file' => 'retro.texas.inc',
),
);
Chapter 3
Let's examine this data. By default a theme hook will be assumed to be implemented
as a theme function named theme_hook_name(). We can override the hook name
using a function key/value inside our austinite array, but please don't confuse
our poor themers; leave the default function name alone. If a theme hook instead
wants to use template implementation, it needs to specify the name of the template
file (without the .tpl.php extension) in the template key/value. Our wonder theme
hook will use a wonder.tpl.php template.
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