PHP Australia Conference 2015

SplSubject::attach

(PHP 5 >= 5.1.0)

SplSubject::attachAttach an SplObserver

Description

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

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

Warning

This function is currently not documented; only its argument list is available.

Parameters

observer

The SplObserver to attach.

Return Values

No value is returned.

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User Contributed Notes 2 notes

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workspace dot development at yahoo dot com
2 years ago
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();
?>
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goran
2 years ago
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)]);
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