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!
compare online pharmacy prices [url=https://safemedsguide.com/#]promo codes for online drugstores[/url] promo codes for online drugstores
Hermanengam
31 Oct 25 at 2:22 pm
двойные рулонные шторы с электроприводом [url=https://rulonnye-shtory-s-elektroprivodom7.ru/]rulonnye-shtory-s-elektroprivodom7.ru[/url] .
rylonnie shtori s elektroprivodom_xwMl
31 Oct 25 at 2:23 pm
сделать онлайн трансляцию мероприятия [url=https://zakazat-onlayn-translyaciyu5.ru]https://zakazat-onlayn-translyaciyu5.ru[/url] .
zakazat onlain translyaciu_ugmr
31 Oct 25 at 2:24 pm
натяжные потолки нижний новгород с установкой [url=http://natyazhnye-potolki-nizhniy-novgorod-1.ru/]http://natyazhnye-potolki-nizhniy-novgorod-1.ru/[/url] .
natyajnie potolki nijnii novgorod_loma
31 Oct 25 at 2:24 pm
[url=https://bioss-ms.ru/]Современная щековая дробилка [/url]— это ключевое оборудование, применяемое для подготовки минерального сырья к дальнейшей переработке. Благодаря современным инженерным решениям она обеспечивает минимальные энергозатраты и устойчивость к износу. Лидеры отрасли постоянно внедряют новые разработки, что делает щековые дробилки основой любого производственного цикла в сфере переработки сырья. Новые инженерные подходы позволяют снизить уровень шума и вибрации. Интеллектуальные системы управления делают эксплуатацию оборудования более безопасной. Новые серии создаются с учетом экологических стандартов, что обеспечивает экологичность производства. Каждый элемент конструкции продуман, чтобы достичь максимальной точности дробления. Такое оборудование востребовано в строительстве, горнодобыче и переработке, обеспечивая высокое качество продукции. За счет оптимального угла захвата и надежных подшипников обеспечивается минимизация простоев. На рынке представлено множество решений, что позволяет подобрать оптимальный вариант под конкретные задачи. Компактные установки удобны для мобильных производств, а интеллектуальные функции и мониторинг позволяют оперативно контролировать производительность. Можно сказать, что современные щековые дробилки становятся важным элементом цифрового производства. Главная тенденция — автоматизация и энергоэффективность, где человеческий фактор минимизируется за счет автоматизации.
https://bioss-ms.ru/
Aaronsiree
31 Oct 25 at 2:24 pm
Hey there! I know this is kinda off topic nevertheless I’d figured I’d ask.
Would you be interested in trading links or maybe guest writing
a blog article or vice-versa? My website addresses
a lot of the same subjects as yours and I think we could greatly benefit from each other.
If you might be interested feel free to shoot me
an e-mail. I look forward to hearing from you!
Excellent blog by the way!
buôn bán nội tạng
31 Oct 25 at 2:24 pm
Формат
Получить больше информации – [url=https://narkologicheskaya-pomoshch-ramenskoe7.ru/]narkologicheskaya-pomoshch-na-domu[/url]
Charlespheva
31 Oct 25 at 2:24 pm
I do not even understand how I finished up right here, however I thought this put up
was good. I don’t understand who you might be however definitely you
are going to a well-known blogger in case you aren’t already.
Cheers!
Tàng trữ chất cấm
31 Oct 25 at 2:25 pm
купить диплом в уфе [url=rudik-diplom15.ru]купить диплом в уфе[/url] .
Diplomi_ryPi
31 Oct 25 at 2:26 pm
affordable medications UK: UkMedsGuide – safe place to order meds UK
HaroldSHems
31 Oct 25 at 2:26 pm
Даже если кажется, что «пройдёт само», при запойных состояниях осложнения нарастают быстро. Перед списком отметим логику: показания к инфузионной терапии определяет врач по совокупности симптомов, хронических заболеваний и текущих показателей. Ниже — типичные ситуации, при которых капельница даёт предсказуемый клинический эффект и снижает риски.
Получить дополнительные сведения – https://kapelnica-ot-zapoya-vidnoe7.ru/
BrianREd
31 Oct 25 at 2:27 pm
купить рулонные шторы в москве [url=http://avtomaticheskie-rulonnye-shtory1.ru]купить рулонные шторы в москве[/url] .
avtomaticheskie rylonnie shtori_otMr
31 Oct 25 at 2:27 pm
При критических симптомах (потеря сознания, сильная одышка, подозрение на инсульт/инфаркт) необходимо звонить 103/112. Мы подключимся к маршрутизации и организуем перевод в стационар.
Получить дополнительную информацию – https://vyvod-iz-zapoya-noginsk7.ru/vyvod-iz-zapoya-deshevo-v-noginske/
JeromeNup
31 Oct 25 at 2:28 pm
карниз электро [url=http://elektrokarniz777.ru]http://elektrokarniz777.ru[/url] .
elektrokarniz _sosr
31 Oct 25 at 2:28 pm
электрокарниз двухрядный [url=https://elektrokarniz797.ru/]elektrokarniz797.ru[/url] .
elektrokarniz_agEi
31 Oct 25 at 2:28 pm
карнизы для штор купить в москве [url=http://elektrokarniz-kupit.ru/]карнизы для штор купить в москве[/url] .
elektrokarniz kypit_lfea
31 Oct 25 at 2:30 pm
сайт натяжной потолок [url=https://natyazhnye-potolki-nizhniy-novgorod-1.ru/]https://natyazhnye-potolki-nizhniy-novgorod-1.ru/[/url] .
natyajnie potolki nijnii novgorod_shma
31 Oct 25 at 2:30 pm
рулонные шторы на окна цена [url=http://rulonnye-shtory-s-elektroprivodom7.ru]рулонные шторы на окна цена[/url] .
rylonnie shtori s elektroprivodom_srMl
31 Oct 25 at 2:30 pm
Когда уместен
Получить дополнительные сведения – http://narkologicheskaya-pomoshch-orekhovo-zuevo7.ru
HarleyMardy
31 Oct 25 at 2:31 pm
pharmacy delivery Ireland
Edmundexpon
31 Oct 25 at 2:32 pm
заказать трансляцию конференции [url=http://www.zakazat-onlayn-translyaciyu5.ru]http://www.zakazat-onlayn-translyaciyu5.ru[/url] .
zakazat onlain translyaciu_momr
31 Oct 25 at 2:32 pm
Estou completamente vidrado por BetorSpin Casino, oferece uma aventura de cassino que orbita como um cometa reluzente. A gama do cassino e simplesmente uma constelacao de prazeres, com slots de cassino tematicos de espaco sideral. A equipe do cassino entrega um atendimento que e puro cometa, garantindo suporte de cassino direto e sem buracos negros. Os ganhos do cassino chegam voando como um asteroide, de vez em quando mais giros gratis no cassino seria uma loucura estelar. Em resumo, BetorSpin Casino vale demais explorar esse cassino para os astronautas do cassino! Vale dizer tambem a plataforma do cassino brilha com um visual que e puro cosmos, o que torna cada sessao de cassino ainda mais estelar.
betorspin giriЕџ|
glimmerfizzytoad7zef
31 Oct 25 at 2:33 pm
tg @‌links_dealer | effective seo links for 888-starz.pl
Jamesselty
31 Oct 25 at 2:34 pm
online pharmacy reviews and ratings: online pharmacy – online pharmacy
HaroldSHems
31 Oct 25 at 2:34 pm
What we’re covering
• Zelensky in Washington: European leaders will join Ukrainian President Volodymyr Zelensky at the White House, as he meets with US President Donald Trump this afternoon. Trump said Zelensky must agree to some of Russia’s conditions — including that Ukraine cede Crimea and agree never to join NATO — for the war to end.
[url=https://kra-34cc.com]kra30[/url]
• Potential security guarantees: At last week’s summit with Trump, Russian President Vladimir Putin agreed to allow security guarantees for Ukraine and made concessions on “land swaps” as part of a potential peace deal, US envoy Steve Witkoff told CNN. Zelensky suggested that such guarantees would need to be stronger than those that “didn’t work” in the past. Russia has yet to mention such agreements.
[url=https://kra30cc.net]kra40 at[/url]
• On the ground: Zelensky condemned Russia’s latest strikes across Ukraine, which killed at least 10 people, saying the Kremlin intends to “humiliate diplomatic efforts” and underscores “why reliable security guarantees are required.”
kra33
https://kra34-at.com
JorgeKesia
31 Oct 25 at 2:34 pm
seven kay casino регистрация севан кей казино официальный сайт применяет лицензию Кюрасао и соответствует требованиям ответственной игры.
BrianFaw
31 Oct 25 at 2:35 pm
naturespirit.click
PHP hook, building hooks in your application – Sjoerd Maessen blog at Sjoerd Maessen blog
naturespirit.click
31 Oct 25 at 2:35 pm
электрические карнизы купить [url=elektrokarniz797.ru]elektrokarniz797.ru[/url] .
elektrokarniz_rqEi
31 Oct 25 at 2:35 pm
Ich bin total angetan von Cat Spins Casino, es verspricht ein einzigartiges Abenteuer. Es gibt unzahlige packende Spiele, mit packenden Live-Casino-Optionen. Er sorgt fur einen starken Einstieg. Erreichbar rund um die Uhr. Die Zahlungen sind sicher und zuverlassig, manchmal mehr regelma?ige Aktionen waren toll. Alles in allem, Cat Spins Casino sorgt fur kontinuierlichen Spa?. Nebenbei die Plattform ist visuell ansprechend, eine Prise Spannung hinzufugt. Ein gro?es Plus sind die sicheren Krypto-Zahlungen, die die Community enger zusammenschwei?en.
Heute besuchen|
OmegaFireis9zef
31 Oct 25 at 2:36 pm
https://ukmedsguide.shop/# trusted online pharmacy UK
Haroldovaph
31 Oct 25 at 2:39 pm
электрокарнизы москва [url=elektrokarniz-kupit.ru]elektrokarniz-kupit.ru[/url] .
elektrokarniz kypit_liea
31 Oct 25 at 2:39 pm
Продвижение сайтов: как повысить видимость и конверсию https://youtube-start.ru/stati/prodvizhenie-sajtov-kak-povysit-vidimost-i-konversiju/
Jeffreyjeofe
31 Oct 25 at 2:41 pm
рулонные шторы на электроприводе [url=https://www.rulonnye-shtory-s-elektroprivodom7.ru]рулонные шторы на электроприводе[/url] .
rylonnie shtori s elektroprivodom_liMl
31 Oct 25 at 2:41 pm
рулонные шторы электрические [url=http://avtomaticheskie-rulonnye-shtory1.ru/]рулонные шторы электрические[/url] .
avtomaticheskie rylonnie shtori_sbMr
31 Oct 25 at 2:42 pm
автоматические карнизы [url=http://www.elektrokarniz777.ru]автоматические карнизы[/url] .
elektrokarniz _ehsr
31 Oct 25 at 2:44 pm
автоматические карнизы для штор [url=http://www.elektrokarniz797.ru]автоматические карнизы для штор[/url] .
elektrokarniz_uhEi
31 Oct 25 at 2:44 pm
стоимость рулонных штор [url=www.avtomaticheskie-rulonnye-shtory1.ru]стоимость рулонных штор[/url] .
avtomaticheskie rylonnie shtori_nxMr
31 Oct 25 at 2:44 pm
электронный карниз для штор [url=www.elektrokarniz-kupit.ru]электронный карниз для штор[/url] .
elektrokarniz kypit_hbea
31 Oct 25 at 2:48 pm
This post is in fact a nice one it assists new the web people, who are wishing for blogging.
kedai pajak emas near me
31 Oct 25 at 2:49 pm
What we’re covering
• Zelensky in Washington: European leaders will join Ukrainian President Volodymyr Zelensky at the White House, as he meets with US President Donald Trump this afternoon. Trump said Zelensky must agree to some of Russia’s conditions — including that Ukraine cede Crimea and agree never to join NATO — for the war to end.
[url=https://kra33-at.cc]kra40 cc[/url]
• Potential security guarantees: At last week’s summit with Trump, Russian President Vladimir Putin agreed to allow security guarantees for Ukraine and made concessions on “land swaps” as part of a potential peace deal, US envoy Steve Witkoff told CNN. Zelensky suggested that such guarantees would need to be stronger than those that “didn’t work” in the past. Russia has yet to mention such agreements.
[url=https://kra34.org]kra31 cc[/url]
• On the ground: Zelensky condemned Russia’s latest strikes across Ukraine, which killed at least 10 people, saying the Kremlin intends to “humiliate diplomatic efforts” and underscores “why reliable security guarantees are required.”
kra38
https://kra31-cc.com
RichardJek
31 Oct 25 at 2:49 pm
потолочник натяжные потолки нижний новгород [url=http://natyazhnye-potolki-nizhniy-novgorod-1.ru/]http://natyazhnye-potolki-nizhniy-novgorod-1.ru/[/url] .
natyajnie potolki nijnii novgorod_rlma
31 Oct 25 at 2:49 pm
прокарниз [url=https://elektrokarniz-kupit.ru/]https://elektrokarniz-kupit.ru/[/url] .
elektrokarniz kypit_jcea
31 Oct 25 at 2:50 pm
организация онлайн трансляций под ключ [url=https://zakazat-onlayn-translyaciyu5.ru]организация онлайн трансляций под ключ[/url] .
zakazat onlain translyaciu_lhmr
31 Oct 25 at 2:51 pm
двойные рулонные шторы с электроприводом [url=https://avtomaticheskie-rulonnye-shtory1.ru]https://avtomaticheskie-rulonnye-shtory1.ru[/url] .
avtomaticheskie rylonnie shtori_rvMr
31 Oct 25 at 2:51 pm
Пришла сегодня посыль с 203им,кол-во ровное,даже показалось больше))) Сделал 1 к 15 самое то,магазу спасибо,процветания и всег благ) https://nastavnik124.ru первую посылочку получил от селера, сервис на вышем уровне не то что у некоторых!!!!!
AustinSkeLs
31 Oct 25 at 2:51 pm
электрокарниз купить [url=www.elektrokarniz797.ru]электрокарниз купить[/url] .
elektrokarniz_icEi
31 Oct 25 at 2:51 pm
compare pharmacy websites: verified online chemists in Australia – verified online chemists in Australia
HaroldSHems
31 Oct 25 at 2:54 pm
rosetemplates – The visual previews are helpful, they give a clear idea of what you’re getting.
Ernie Knab
31 Oct 25 at 2:54 pm
https://t.me/s/ud_Riobet/59
MichaelPione
31 Oct 25 at 2:54 pm
рулонные шторы на электроприводе [url=avtomaticheskie-rulonnye-shtory1.ru]рулонные шторы на электроприводе[/url] .
avtomaticheskie rylonnie shtori_wtMr
31 Oct 25 at 2:54 pm