Theme Registry

• File Structure
• Theme Functions
• Theme Process and Preprocess Functions (.vars.php)
• Theme Templates
• Theme Hook Naming Conventions

File Structure

The Drupal Bootstrap base theme handles some very complex theme registry alterations to assist with the organization and maintenance of its source code.

By leveraging Drupal's ability to include files only when a specific theme hook is invoked, this base theme is able to reduce its per page PHP memory footprint. It also allows for easier maintenance and organization with as many overrides as this base theme implements.

This base theme provides a multitude of [pre]process functions, theme functions and templates stored inside the ./bootstrap/templates folder. The base theme will traverse all folders inside this folder as well as a subtheme's ./subtheme/templates folder.

Over time this base theme has grown exponentially and this type of change will help ensure future growth, without sacrificing performance. It's an easy and hierarchical folder structure based on the module they originated from.

Sub-themes, while not required to do so, can emulate this same type of file structure and take advantage of this base theme's unique ability.

Rest assured though, there is no need to structure your sub-theme this way. If you feel more comfortable storing everything in your sub-theme's 'template.php file, feel free to do so.

It's highly recommended, however, that you at least understand how the base theme structures its functions and templates so you can easily copy them over to your sub-theme should the need arise.

Theme Functions (.func.php) {#theme-functions}

Theme functions can be be stored in a dedicated file. These files should end in a .func.php extension where the name of the file relates to the base "theme hook" being invoked. For example: the theme hook breadcrumb is rendered by the bootstrap_breadcrumb() theme function located in the ./bootstrap/templates/system/breadcrumb.func.php file.

{.help-block} See related sub-topic below for a list of functions.

Theme Process and Preprocess Functions (.vars.php) {#theme-preprocess}

Theme process and preprocess functions can be stored in a dedicated file. These files must end with a .vars.php extension where the name of the file relates to the base "theme hook" being invoked.

For example: the theme hook page has both the process function bootstrap_process_page() and the preprocess function bootstrap_preprocess_page() which are located in the ./bootstrap/templates/system/page.vars.php file.

This file should also contain any helper functions that are specific to the theme hook as well. If a function becomes too large, break it apart so it can become more legible.

{.help-block} See related sub-topic below for a list of functions.

Theme Templates (.tpl.php) {#theme-templates}

Theme template files should end with a .tpl.php extension where the name of the file relates to the base "theme hook" being invoked. For example: the template for the theme hook page is located at ./bootstrap/templates/system/page.tpl.php.

{.help-block} See related sub-topic below for a list of templates.

Theme Hook Naming Conventions

As a general rule, theme hooks must convert all underscores (_) to hyphens (-) for the file name. This can sometimes be especially confusing for some at first. Any time a file name has been changed, you must also rebuild the theme registry. The easiest way to do this is to "Clear all caches" on the admin/config/development/performance page.

The exception for this rule would be theme function (.func.php) and [pre]process function (.vars.php) files. These file names should only be named using the base theme hook (using the general rule).

Theme hook suggestions should not be used in the file name, but rather their suggestion functions placed inside the base theme hook .func.php or .vars.php file. An example of this would be the bootstrap_menu_tree__primary() theme function where the base theme hook is menu_tree (the hook name before __) and located in the ./bootstrap/templates/menu/menu-tree.func.php file.