History: Events

            !Events
Events can be triggered in Tiki during execution of functions. A general usage is to trigger events in service controllers.
Events call a [http://stackoverflow.com/questions/9596276/how-to-explain-callbacks-in-plain-english-how-are-they-different-from-calling-o|callback function ]
Events can be chained
((Activities)) are triggered event instances that are configured to be recorded. Event instances are not automatically recorded (except for some basic events), you need to set up an activity rule if you want this to happen. Activities can be displayed in [https://doc.tiki.org/Activity+Stream|activity streams]. 
Events are not log entries.
Tiki events are defined in the source code, so if you want to setup a new event, you need to modify the definition file. 
!!Definitions 
 {CODE()}lib/setup/events.php{CODE}

An event is definded as below:
||event name|a unique name for the event. Example: tiki.comment.update. 
priority|Allows events to be forced to execute after others. For example,  normal priorities may alter data, but indexing should not happen until all data has been modified. Default priority is 0. Priorities are numeric, false indicates that the event executes at all levels. This is used for chaining and happens transparently when using bind() with an event as the callback.
callback| the name of the callback function to be executed.
arguments| arguments to be passed to the callback function||

When defining events it is important to bind and chain them (see function ''bind'' and ''bindPriority'' in the Library)
__function bind__ binds an event at normal priority and handles event chaining.
__function bindPriority__ binds the event at a specific priority
Binding can:
* point to another event
* defer to a library with a function within that library
* call a service controller function
* be delegated to another library/controller

{CODE()}
$events = TikiLib::events();
$defer = function ($lib, $function ) {
	return Tiki_Event_Lib::defer($lib, $function);
};

//single binding to another event
$events->bind('tiki.comment.post', 'tiki.comment.save');

//multiple binding by deferring to a library and a function within that library
$events->bind('tiki.trackeritem.save', $defer('trk', 'update_tracker_summary'));
$events->bind('tiki.trackeritem.save', $defer('trk', 'invalidate_item_cache'));

// binding using a service controller
$events->bind('tiki.trackeritem.create', ['Services_MustRead_Controller', 'handleItemCreation']);

//delegated binding
TikiLib::lib('goalevent')->bindEvents($events);

{CODE}
!!Library
{CODE()}lib/core/Tiki/Event/Manager.php{CODE}

!!How to use
In a service controller call the trigger function and supply the necessary inputs
{CODE()}
TikiLib::events()->trigger('tiki.comment.update', array(
					'type' => $comment['objectType'],
					'object' => $comment['object'],
					'title' => $title,
					'comment' => $threadId,
					'user' => $GLOBALS['user'],
					'content' => $data,
					'index_handled' => true,
				));
{CODE}