Create new Hooks in Drupal 7

Question

I'm not looking about how to implement an existing hook, but rather to create a new type of hook. Let's say the hook hook_node_load() exists. I want to create something like hook_node_preload(), that fires before the node is loaded.

I've searched and can't seem to find out where in the Drupal code hooks are being fired. I assume it's something like module_invoke_all() or something like that? But I'm not sure where it's called.

Answer 1

Drupal hooks are fired all over the place, throughout all of the Drupal process. There isn't one place that calls all of the hooks.

Below is a list of some of the functions from the Drupal core that create hooks:

http://api.drupal.org/api/drupal/includes%21module.inc/function/calls/module_invoke_all/7

In the case of hook_node_load(), it is called from the entity.inc file located at includes/entity.inc, at line 334.

foreach (module_implements($this->entityInfo['load hook']) as $module) {
  call_user_func_array($module . '_' . $this->entityInfo['load hook'], $args);
}