DoliTicketing/custom/documentfollower/class/actions_documentfollower.class.php

<?php

class ActionsDocumentFollower
{ 
	/**
	 * Overriding the doActions function : replacing the parent function with the one below
	 *
	 * @param   array()         $parameters     Hook metadatas (context, etc...)
	 * @param   CommonObject    &$object        The object to process (an invoice if you are in invoice module, a propale in propale's module, etc...)
	 * @param   string          &$action        Current action (if set). Generally create or edit or null
	 * @param   HookManager     $hookmanager    Hook manager propagated to allow calling another hook
	 * @return  int                             < 0 on error, 0 on success, 1 to replace standard code
	 */
	function doActions($parameters, &$object, &$action, $hookmanager)
	{
		$error = 0; // Error counter
		$myvalue = 'test'; // A result value
        /*
		print_r($parameters);
		echo "action: " . $action;
		print_r($object);
        die;
        */

		if (in_array('documentFollowerEmailTemplateType', explode(':', $parameters['context'])))
		{
		}

		if (!$error)
		{
			$this->results = array('myreturn' => $myvalue);
			$this->resprints = 'A text to show';
			return 0; // or return 1 to replace standard code
		}
		else
		{
			$this->errors[] = 'Error message';
			return -1;
		}
	}
}