Prevent trigger of other hook_preprocess_HOOK()

Question

Is there a way to prevent other preprocess hooks from being triggered?

I have a Drupal 8 hook_preprocess_HOOK() implementation, and I'm doing some alterations. There will be other modules with same hook, and I need the other preprocess hooks not to alter my changes to $variables.

The only options I have are:

• Rely on weights system, which still could cause problems
• Set a value inside $variables and prevent other modules from doing their thing if the variable is set

Answer 1

You can disable hooks via hook_module_implements_alter().

function MYMODULE_module_implements_alter(&$implementations, $hook) {
  if ($hook == 'preprocess_page') {
    unset($implementations['module_foo']);
    unset($implementations['module_bar']);
  }
}

Answer 2

Here's an implementation for Drupal 9 that makes MYMODULE_preprocess_image_style() run first:

/**
 * Implements hook_theme_registry_alter().
 *
 * Makes MYMODULE_preprocess_image_style() run first.
 */
function MYMODULE_theme_registry_alter(&$theme_registry) {
  $themeKey = 'image_style';
  if (isset($theme_registry[$themeKey]['preprocess functions'])) {
    $fname = "MYMODULE_preprocess_$themeKey";
    $pf = &$theme_registry[$themeKey]['preprocess functions'];
    $index = array_search($fname, $pf);
    if ($index) {
      unset($pf[$index]);
      array_unshift($pf, $fname);
    }
  }
}

Answer 3

Preprocess hooks (and specifically hook_preprocess_page) are not subject to hook_module_implements_alter, even if they are implemented by modules. However, they can be adjusted by using hook_theme_registry_alter as suggested by @jonhattan above. Look in the $theme_registrary['page']['preprocess functions'] for the indexed array of implementations.

Note: Tested with Drupal 9.3.8.