May 26, 2018
PEAR dispatch notifications using PHP callbacks
The Event_Dispatcher acts as a notification dispatch table. It is used to notify other objects of interesting things. This information is encapsulated in Event_Notification objects. Client objects register themselves with the Event_Dispatcher as observers of specific notifications posted by other objects. When an event occurs, an object posts an appropriate notification to the Event_Dispatcher. The Event_Dispatcher dispatches a message to each registered observer, passing the notification as the sole argument.