Setting up variables for use in a template (preprocess and process functions)
The main role of the preprocessor is to set up variables to be placed within the template (.tpl.php) files. Plain theme functions do not interact with preprocessors.
- Preprocessors are also used for providing template suggestions.
- In versions 5 and below, the function _phptemplate_variables served the same purpose. It has been deprecated in 6.
- Prior to Drupal 6.7, for your theme to have its preprocessors recognized, the template associated with the hook had to exist inside the theme. When a default template exists, copy it to your theme and clear the registry (or you should really be upgrading to a later version of Drupal anyway for security reasons, at which point you don't have to worry about this).