SplSubject::attach

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

SplSubject::attach — Attach an SplObserver

说明

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

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

警告

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。

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用户贡献的备注 2 notes

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workspace dot development at yahoo dot com ¶

13 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(); 
?>

down

goran ¶

13 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)]);