SplSubject::attach

(PHP 5 >= 5.1.0, PHP 7, PHP 8)

SplSubject::attach — Attach an SplObserver

说明

abstract public SplSubject::attach ( SplObserver $observer ) : void

Attaches an SplObserver so that it can be notified of updates.

Warning

本函数还未编写文档，仅有参数列表。

参数

observer

The SplObserver to attach.

返回值

没有返回值。

User Contributed Notes

workspace dot development at yahoo dot com 02-Dec-2011 08:46
i think that Observer pattern is always implemented as "static" to be called from any scope, for example:
<?php
class Observer {
     //attach here the caller's scope
     private static $stackTrace = array( );
     public static function wasTriggeredOnce() {
          //...if is not in the stack, then:
          self::$stackTrace[] = max( debug_backtrace( ) );
     }
}

class YourFramework {

     public function launchPlatform() {

          //could not let user to launch application twice!
          Observer::wasTriggeredOnce();
     }
}
//cause is static
Observer::hereIsnoNeedToInstantiateAgain();
?>
goran 17-Oct-2011 12:54
The most obvious storage type for observers (stored in attach()) is array. In order to be able to detach attached objects, you should be able to identify it inside observer storage.

I suggest you attach observers this way:

$this->_observers[spl_object_hash($observer)] = $observer;

so you can detach it later if you need:

unset($this->_observers[spl_object_hash($observer)]);