PHP hook, building hooks in your application
Introduction
One of the real challenges in building any type of framework, core or application is making it possible for the developers to hook into the business logic at specific points. Since PHP is not event based, nor it works with interrupts you have to come up an alternative.
The test case
Lets assume we are the main developers of a webshop framework. Programmers can use our framework to build complete webshops. Programmers can manage the orders that are placed on the webshop with the order class. The order class is part of our framework and we don’t want it to be extended by any programmer. However we don’t want to limit to programmers in their possibilities to hook into the orders process.
For example programmers should be able to send an email to the webshopowner if an order changes from one specific delivery status to another. This functionality is not part of the default behavior in our framework and is custom for the progammers webshop implementation.
Like said before, PHP doesn’t provide interrupts or real events so we need to come up with another way to implement hooks into our application. Lets take a look at the observer pattern.
Implementing the Observer pattern
The observer pattern is a design-pattern that describes a way for objects to be notified to specific state-changes in objects of the application.
For the first implementation we can use SPL. The SPL provides in two simple objects:
SPLSubject
- attach (new observer to attach)
- detach (existing observer to detach)
- notify (notify all observers)
SPLObserver
- update (Called from the subject (i.e. when it’s value has changed).
iOrderRef = $iOrderRef;
// Get order information from the database or an other resources
$this->iStatus = Order::STATUS_SHIPPED;
}
/**
* Attach an observer
*
* @param SplObserver $oObserver
* @return void
*/
public function attach(SplObserver $oObserver)
{
$sHash = spl_object_hash($oObserver);
if (isset($this->aObservers[$sHash])) {
throw new Exception('Observer is already attached');
}
$this->aObservers[$sHash] = $oObserver;
}
/**
* Detach observer
*
* @param SplObserver $oObserver
* @return void
*/
public function detach(SplObserver $oObserver)
{
$sHash = spl_object_hash($oObserver);
if (!isset($this->aObservers[$sHash])) {
throw new Exception('Observer not attached');
}
unset($this->aObservers[$sHash]);
}
/**
* Notify the attached observers
*
* @param string $sEvent, name of the event
* @param mixed $mData, optional data that is not directly available for the observers
* @return void
*/
public function notify()
{
foreach ($this->aObservers as $oObserver) {
try {
$oObserver->update($this);
} catch(Exception $e) {
}
}
}
/**
* Add an order
*
* @param array $aOrder
* @return void
*/
public function delete()
{
$this->notify();
}
/**
* Return the order reference number
*
* @return int
*/
public function getRef()
{
return $this->iOrderRef;
}
/**
* Return the current order status
*
* @return int
*/
public function getStatus()
{
return $this->iStatus;
}
/**
* Update the order status
*/
public function updateStatus($iStatus)
{
$this->notify();
// ...
$this->iStatus = $iStatus;
// ...
$this->notify();
}
}
/**
* Order status handler, observer that sends an email to secretary
* if the status of an order changes from shipped to delivered, so the
* secratary can make a phone call to our customer to ask for his opinion about the service
*
* @package Shop
*/
class OrderStatusHandler implements SplObserver
{
/**
* Previous orderstatus
* @var int
*/
protected $iPreviousOrderStatus;
/**
* Current orderstatus
* @var int
*/
protected $iCurrentOrderStatus;
/**
* Update, called by the observable object order
*
* @param Observable_Interface $oSubject
* @param string $sEvent
* @param mixed $mData
* @return void
*/
public function update(SplSubject $oSubject)
{
if(!$oSubject instanceof Order) {
return;
}
if(is_null($this->iPreviousOrderStatus)) {
$this->iPreviousOrderStatus = $oSubject->getStatus();
} else {
$this->iCurrentOrderStatus = $oSubject->getStatus();
if($this->iPreviousOrderStatus === Order::STATUS_SHIPPED && $this->iCurrentOrderStatus === Order::STATUS_DELIVERED) {
$sSubject = sprintf('Order number %d is shipped', $oSubject->getRef());
//mail('secratary@example.com', 'Order number %d is shipped', 'Text');
echo 'Mail sended to the secratary to help her remember to call our customer for a survey.';
}
}
}
}
$oOrder = new Order(26012011);
$oOrder->attach(new OrderStatusHandler());
$oOrder->updateStatus(Order::STATUS_DELIVERED);
$oOrder->delete();
?>
There are several problems with the implementation above. To most important disadvantage is that we have only one update method in our observer. In this update method we don’t know when and why we are getting notified, just that something happened. We should keep track of everything that happens in the subject. (Or use debug_backtrace… just joking, don’t even think about using it that way ever!).
Taking it a step further, events
Lets take a look at the next example, we will extend the Observer implementation with some an additional parameter for the eventname that occured.
Finishing up, optional data
iOrderRef = $iOrderRef;
// Get order information from the database or something else...
$this->iStatus = Order::STATUS_SHIPPED;
}
/**
* Attach an observer
*
* @param Observer_Interface $oObserver
* @return void
*/
public function attachObserver(Observer_Interface $oObserver)
{
$sHash = spl_object_hash($oObserver);
if (isset($this->aObservers[$sHash])) {
throw new Exception('Observer is already attached');
}
$this->aObservers[$sHash] = $oObserver;
}
/**
* Detach observer
*
* @param Observer_Interface $oObserver
* @return void
*/
public function detachObserver(Observer_Interface $oObserver)
{
$sHash = spl_object_hash($oObserver);
if (!isset($this->aObservers[$sHash])) {
throw new Exception('Observer not attached');
}
unset($this->aObservers[$sHash]);
}
/**
* Notify the attached observers
*
* @param string $sEvent, name of the event
* @param mixed $mData, optional data that is not directly available for the observers
* @return void
*/
public function notifyObserver($sEvent, $mData=null)
{
foreach ($this->aObservers as $oObserver) {
try {
$oObserver->update($this, $sEvent, $mData);
} catch(Exception $e) {
}
}
}
/**
* Add an order
*
* @param array $aOrder
* @return void
*/
public function add($aOrder = array())
{
$this->notifyObserver('onAdd');
}
/**
* Return the order reference number
*
* @return int
*/
public function getRef()
{
return $this->iOrderRef;
}
/**
* Return the current order status
*
* @return int
*/
public function getStatus()
{
return $this->iStatus;
}
/**
* Update the order status
*/
public function updateStatus($iStatus)
{
$this->notifyObserver('onBeforeUpdateStatus');
// ...
$this->iStatus = $iStatus;
// ...
$this->notifyObserver('onAfterUpdateStatus');
}
}
/**
* Order status handler, observer that sends an email to secretary
* if the status of an order changes from shipped to delivered, so the
* secratary can make a phone call to our customer to ask for his opinion about the service
*
* @package Shop
*/
class OrderStatusHandler implements Observer_Interface
{
protected $iPreviousOrderStatus;
protected $iCurrentOrderStatus;
/**
* Update, called by the observable object order
*
* @param Observable_Interface $oObservable
* @param string $sEvent
* @param mixed $mData
* @return void
*/
public function update(Observable_Interface $oObservable, $sEvent, $mData=null)
{
if(!$oObservable instanceof Order) {
return;
}
switch($sEvent) {
case 'onBeforeUpdateStatus':
$this->iPreviousOrderStatus = $oObservable->getStatus();
return;
case 'onAfterUpdateStatus':
$this->iCurrentOrderStatus = $oObservable->getStatus();
if($this->iPreviousOrderStatus === Order::STATUS_SHIPPED && $this->iCurrentOrderStatus === Order::STATUS_DELIVERED) {
$sSubject = sprintf('Order number %d is shipped', $oObservable->getRef());
//mail('secratary@example.com', 'Order number %d is shipped', 'Text');
echo 'Mail sended to the secratary to help her remember to call our customer for a survey.';
}
}
}
}
$oOrder = new Order(26012011);
$oOrder->attachObserver(new OrderStatusHandler());
$oOrder->updateStatus(Order::STATUS_DELIVERED);
$oOrder->add();
?>
Now we are able to take action on different events that occur.
Disadvantages
Although this implementation works quite well there are some drawbacks. One of those drawbacks is that we need to dispatch an event in our framework, if we don’t programmers can’t hook into our application. Triggering events everywhere give us a small performance penalty however I do think this way of working gives the programmers a nice way to hook into your application on those spots that you want them to hook in.
Just for the record
Notice that this code is just an example and can still use some improvements, for example: each observer is initialized even it will maybe never be notified, therefore I suggest to make use of lazy in some cases for loading the objects. There are other systems to hook into an application, more to follow!
Мега даркнет Мега даркнет Мега сайт Мега онион Мега ссылка Mega даркнет Mega сайт Mega онион Mega ссылка Mega darknet Mega onion
RichardPep
15 Sep 25 at 4:54 pm
Definitely consider that that you said. Your favorite justification appeared to
be on the web the simplest thing to have in mind of.
I say to you, I definitely get irked whilst other people consider worries that they just do not recognize about.
You managed to hit the nail upon the highest as well as defined out
the whole thing without having side-effects , other folks can take
a signal. Will probably be again to get more. Thanks
outfit dominan musim sekarang
15 Sep 25 at 4:55 pm
Unquestionably believe that which you said. Your favorite justification appeared to be on the web the simplest thing
to be aware of. I say to you, I certainly get irked while people consider worries that they plainly
don’t know about. You managed to hit the nail upon the top and
defined out the whole thing without having side effect , people can take
a signal. Will probably be back to get more. Thanks
my web-site :: facelift cost South Africa
facelift cost South Africa
15 Sep 25 at 5:00 pm
Way cool! Some extremely valid points! I appreciate you writing this article plus the rest of the website is also very good.
Gain Mode AI
15 Sep 25 at 5:01 pm
Узнайте максимум о компании Restyle-Авто — современный автоцентр, широкий выбор авто, лояльная ценовая политика и надежные сделки! Посетите [url=https://restyle-avto.ru]https://restyle-avto.ru[/url] и узнайте продажу авто. Подбираете машину или лучшее предложение — компания предлагает комиссионную продажу, обмен Trade-In и удобную доставку. Ищете выгодную покупку — здесь найдёте доступные цены и честные условия.
Spravkipse
15 Sep 25 at 5:03 pm
Fabulous, what a web site it is! This weblog gives helpful information to us, keep it up.
tips latihan sepak bola Amerika
15 Sep 25 at 5:05 pm
кракен зеркало актуальное позволяет обойти возможные блокировки и получить доступ к маркетплейсу. [url=https://twofold.pt/]кракен магазин[/url] необходимо искать через проверенные источники, чтобы избежать фишинговых сайтов. кракен рабочая ссылка должно обновляться регулярно для обеспечения непрерывного доступа.
onion – главная особенность Кракен.
KrakenOthex
15 Sep 25 at 5:06 pm
Мы готовы предложить дипломы любой профессии по приятным ценам. Приобретение диплома, подтверждающего обучение в ВУЗе, – это выгодное решение. Купить диплом университета: [url=http://albaniaproperty.al/author/dorthytroedel/]albaniaproperty.al/author/dorthytroedel[/url]
Mazrcmm
15 Sep 25 at 5:08 pm
https://emilioipae656.timeforchangecounselling.com/state
Aprobar un test antidoping puede ser un desafio. Por eso, ahora tienes un suplemento innovador con respaldo internacional.
Su formula premium combina nutrientes esenciales, lo que estimula tu organismo y disimula temporalmente los trazas de sustancias. El resultado: un analisis equilibrado, lista para pasar cualquier control.
Lo mas valioso es su accion rapida en menos de 2 horas. A diferencia de detox irreales, no promete limpiezas magicas, sino una herramienta puntual que te respalda en situaciones criticas.
Miles de estudiantes ya han experimentado su seguridad. Testimonios reales mencionan envios en menos de 24 horas.
Si necesitas asegurar tu resultado, esta alternativa te ofrece respaldo.
JuniorShido
15 Sep 25 at 5:09 pm
https://penzu.com/p/7594b1f6f8e9d84e
JeffreyAmipt
15 Sep 25 at 5:10 pm
https://www.tripadvisor.com/Profile/Adventure45664402473
Lloydnouck
15 Sep 25 at 5:11 pm
купить диплом о среднем [url=www.educ-ua2.ru]купить диплом о среднем[/url] .
Diplomi_gqOt
15 Sep 25 at 5:11 pm
I could not resist commenting. Well written!
Feel free to surf to my website; matcha tea for focus
matcha tea for focus
15 Sep 25 at 5:14 pm
https://intimgesund.com/# Intim Gesund
EnriqueVox
15 Sep 25 at 5:14 pm
I’m crazy about Wazamba Casino, it’s an online casino that roars like a jungle beast. There’s a stampede of captivating casino games, supporting casino games optimized for cryptocurrencies. The casino team delivers support worthy of a jungle king, with help that shines like a tribal torch. Casino payments are secure and smooth, however more free spins at the casino would be wild. In summary, Wazamba Casino is a gem for casino fans for fans of modern casino slots! By the way the casino platform shines with a style as bold as a jaguar, making every casino session even wilder.
wazamba free|
zanyglitterquokka9zef
15 Sep 25 at 5:15 pm
Je suis accro a Tortuga Casino, il propose une aventure de casino qui navigue comme un galion au vent. Les options de jeu au casino sont riches et aventureuses, incluant des jeux de table de casino d’une elegance de flibustier. Le personnel du casino offre un accompagnement digne d’un pirate legendaire, avec une aide qui hisse les voiles. Les retraits au casino sont rapides comme un abordage, par moments des bonus de casino plus frequents seraient epiques. Globalement, Tortuga Casino est un tresor pour les fans de casino pour les amoureux des slots modernes de casino ! Par ailleurs la navigation du casino est intuitive comme une boussole, ajoute une touche de legende pirate au casino.
tortuga casino numГ©ro de tГ©lГ©phone|
zanyglitterparrot7zef
15 Sep 25 at 5:17 pm
Great work! That is the type of information that are meant to be shared
around the internet. Disgrace on Google for no longer positioning this post higher!
Come on over and seek advice from my website
. Thanks =)
web page
15 Sep 25 at 5:19 pm
Je trouve absolument enivrant Unibet Casino, ca degage une ambiance de jeu aussi petillante qu’un orchestre en feu. La selection du casino est une symphonie de plaisirs, offrant des sessions de casino en direct qui chantent comme un ch?ur. Les agents du casino sont rapides comme une note staccato, avec une aide qui resonne comme une symphonie. Les paiements du casino sont securises et fluides, parfois plus de tours gratuits au casino ce serait melodique. Dans l’ensemble, Unibet Casino est un joyau pour les fans de casino pour les amoureux des slots modernes de casino ! Par ailleurs le design du casino est une fresque visuelle harmonieuse, facilite une experience de casino enchanteresse.
paris turf sur unibet|
whackyglitterlemur6zef
15 Sep 25 at 5:20 pm
slotguru.ru
JerryBic
15 Sep 25 at 5:22 pm
slotguru.ru
JerryBic
15 Sep 25 at 5:25 pm
can i order cheap doxycycline price
generic name doxycycline
15 Sep 25 at 5:26 pm
диплом бакалавра купить стоимость [url=www.educ-ua5.ru]диплом бакалавра купить стоимость[/url] .
Diplomi_bbKl
15 Sep 25 at 5:27 pm
Experience the ultimate relaxation with Hiso Massage’s best Nuru massage in Sukhumvit 31, Bangkok, Thailand. Our skilled therapists use premium Nuru gel for smooth, full-body gliding, relieving stress, tension, and promoting wellness. Enjoy a private, luxurious, and unforgettable massage experience today.
[url=https://www.hisomassage.com/]best nuru massage[/url]
nurumassages
15 Sep 25 at 5:28 pm
https://blaukraftde.shop/# gГјnstigste online apotheke
EnriqueVox
15 Sep 25 at 5:32 pm
купить старый диплом техникума [url=http://educ-ua2.ru]купить старый диплом техникума[/url] .
Diplomi_doOt
15 Sep 25 at 5:36 pm
Simply desire to say your article is as astounding. The clearness
on your post is just spectacular and that i can think you are an expert on this subject.
Fine along with your permission allow me to clutch your RSS feed to stay updated with drawing close post.
Thank you a million and please keep up the rewarding
work.
Igenics
15 Sep 25 at 5:38 pm
карнизы для штор купить в москве [url=www.karnizy-s-elektroprivodom-cena.ru]карнизы для штор купить в москве[/url] .
karnizi s elektroprivodom cena_ixkr
15 Sep 25 at 5:39 pm
Казино Драгон Мани – яркая платформа с захватывающими играми,
щедрыми бонусами и удобным интерфейсом. Здесь вы найдёте слоты,
рулетку и другие азартные игры с высоким качеством графики и
быстрыми выплатами
драгон мани
Davidduh
15 Sep 25 at 5:40 pm
Узнайте все подробности о автосалоне Restyle — современный автоцентр, широкий выбор авто, выгодные цены и надежные сделки! Перейдите на [url=https://restyle-avto.ru]https://restyle-avto.ru[/url] и изучите автомобили на складе. Ищете новый автомобиль или лучшее предложение — дилерский центр предлагает продажу с пробегом, обмен Trade-In и клиентскую поддержку. Хотите без лишних хлопот — здесь найдёте лучшие условия покупки и гарантированное качество.
Spravkihft
15 Sep 25 at 5:42 pm
Казино Драгон Мани – яркая платформа с захватывающими играми,
щедрыми бонусами и удобным интерфейсом. Здесь вы найдёте слоты,
рулетку и другие азартные игры с высоким качеством графики и
быстрыми выплатами
dragonmoney
Davidduh
15 Sep 25 at 5:43 pm
Mega darknet Мега даркнет Мега сайт Мега онион Мега ссылка Mega даркнет Mega сайт Mega онион Mega ссылка Mega darknet Mega onion
RichardPep
15 Sep 25 at 5:46 pm
Строительный портал https://krovlyaikrysha.ru база знаний и идей. Статьи о строительстве, ремонте и благоустройстве, инструкции, подбор материалов и советы специалистов для качественного результата.
Haroldchept
15 Sep 25 at 5:52 pm
Всё про ремонт https://gbu-so-svo.ru и строительство — статьи, инструкции и советы для мастеров и новичков. Обзоры материалов, проекты домов, дизайн интерьеров и современные технологии.
DouglasVab
15 Sep 25 at 5:52 pm
schnelle lieferung tadalafil tabletten: tadalafil 20mg preisvergleich – online apotheke deutschland
Israelpaync
15 Sep 25 at 5:53 pm
купить диплом в житомире [url=https://educ-ua5.ru]https://educ-ua5.ru[/url] .
Diplomi_rfKl
15 Sep 25 at 5:53 pm
medikament ohne rezept notfall: online apotheke – beste online-apotheke ohne rezept
Donaldanype
15 Sep 25 at 5:54 pm
Автомобильный портал https://ivanmotors.ru всё о машинах в одном месте. Тест-драйвы, обзоры, аналитика авторынка и советы специалистов. Актуальные события мира авто для водителей и экспертов.
FrankMag
15 Sep 25 at 5:54 pm
Pillole di abilify generico
Posso ottenere abilify senza assicurazione
15 Sep 25 at 5:57 pm
I love what you guys tend to be up too. This kind of clever work and reporting!
Keep up the wonderful works guys I’ve incorporated you guys to my personal blogroll.
My web blog: wholesale matcha supplier
wholesale matcha supplier
15 Sep 25 at 6:02 pm
can i order generic vermox
get generic vermox pills
15 Sep 25 at 6:04 pm
I pay a visit everyday a few web sites and sites to read articles or reviews, however this
blog offers feature based posts.
new casino sites
15 Sep 25 at 6:06 pm
I like reading through an article that will make men and
women think. Also, thanks for permitting me to comment!
fast withdrawal casinos
15 Sep 25 at 6:09 pm
купить рулонные шторы в москве [url=avtomaticheskie-rulonnye-shtory5.ru]купить рулонные шторы в москве[/url] .
avtomaticheskie rylonnie shtori_arsr
15 Sep 25 at 6:12 pm
рулонные шторы на заказ цена [url=www.elektricheskie-rulonnye-shtory15.ru]www.elektricheskie-rulonnye-shtory15.ru[/url] .
elektricheskie rylonnie shtori_bgEi
15 Sep 25 at 6:13 pm
https://myrentacar.site/
https://myrentacar.site/
15 Sep 25 at 6:13 pm
автоматические карнизы [url=https://karnizy-s-elektroprivodom-cena.ru/]автоматические карнизы[/url] .
karnizi s elektroprivodom cena_pykr
15 Sep 25 at 6:14 pm
https://red-dead.ru/ru/
DanielSoOni
15 Sep 25 at 6:15 pm
Мы изготавливаем дипломы любой профессии по доступным тарифам. Приобретение документа, который подтверждает обучение в ВУЗе, – это рациональное решение. Приобрести диплом о высшем образовании: [url=http://desteg.getbb.ru/ucp.php?mode=login&sid=0ea0a6cea130298a98f532f82727f4db/]desteg.getbb.ru/ucp.php?mode=login&sid=0ea0a6cea130298a98f532f82727f4db[/url]
Mazrfas
15 Sep 25 at 6:16 pm
электрокарнизы москва [url=https://karniz-s-elektroprivodom-kupit.ru/]karniz-s-elektroprivodom-kupit.ru[/url] .
karniz s elektroprivodom kypit_dsEr
15 Sep 25 at 6:16 pm
Thankfulness to my father who told me regarding this weblog, this website
is truly remarkable.
Leale Investi
15 Sep 25 at 6:17 pm