plugins.md

Plugins

Cavalcade is fully extensible. For additional functionality for the plugin side of Cavalcade, you can use the existing hooks and system in WordPress.

Plugins in Cavalcade Runner work a little differently. While most functionality can be handled in WordPress, meta-level reporting and logging of jobs is best done in the Runner.

Since the Runner is a separate, non-WordPress daemon, it includes its own plugin system. This system will be familiar to anyone who has written a WordPress plugin before.

Writing a Plugin

The only file Cavalcade loads from your project is wp-config.php, so all plugin code for Cavalcade needs to be registered before your require 'wp-settings.php' line.

To add a hook, call HM\Cavalcade\Runner::instance()->hooks->register(). This function is almost identical to the add_filter() function in WordPress:

/**
 * Register a callback for a hook.
 *
 * @param string $hook Hook to register callback for.
 * @param callable $callback Function to call when hook is triggered.
 * @param int $priority Priority to register at.
 */
public function register( $hook, $callback, $priority = 10 );

Hook Naming

The best place to find hooks to use is to read the source code directly.

Hooks are named Class.method.action, where Class is the class name excluding the HM\Cavalcade\Runner, and with \ replaced with .. This ensures you know exactly where a hook is defined.

Adding Your Own Hooks

You can add your own hooks to your plugins, if you want to allow others to extend them:

/**
 * Run a hook's callbacks.
 *
 * @param string $hook Hook to run.
 * @param mixed $value Main value to pass.
 * @param mixed ...$args Other arguments to pass.
 * @return mixed Filtered value after running through callbacks.
 */
public function run( $hook, $value = null, ...$args );