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!
кракен
кракен зеркало
JamesDaync
26 Oct 25 at 7:04 pm
Fastidious respond in return of this question with firm arguments and explaining
all on the topic of that.
seo
26 Oct 25 at 7:06 pm
Ukrainian President Volodymyr Zelensky condemned Russian attacks on the Ukrainian regions of Kharkiv, Zaporizhzhia and Sumy on Monday, saying that the Kremlin intends to “humiliate diplomatic efforts” just hours before European leaders visit the White House.
[url=https://kra-42at.com]kra39 at[/url]
“The Russian war machine continues to destroy lives despite everything,” Zelensky said in a statement, hours before he’s due to meet US President Donald Trump in the Oval Office. “That is precisely why we are seeking assistance to put an end to the killings. That is why reliable security guarantees are required. That is why Russia should not be rewarded for its participation in this war.”
[url=https://kra-41-cc.net]kra42[/url]
“Everyone seeks dignified peace and true security,” the Ukrainian president said. “And at this very moment, the Russians are attacking Kharkiv, Zaporizhzhia, the Sumy region, and Odesa, destroying residential buildings and our civilian infrastructure.”
At least seven people were killed in Russia’s attack? on Kharkiv and a further three killed in the ballistic missile strike on the city of Zaporizhzhia, with scores more injured, according to Ukrainian authorities.
“This was a demonstrative and cynical Russian strike,” Zelensky added.
kra42 сс
https://kra41-at.com
KeithCrima
26 Oct 25 at 7:06 pm
кракен ссылка
kraken onion
Henryamerb
26 Oct 25 at 7:06 pm
медицинская техника [url=http://medicinskaya-tehnika.ru]медицинская техника[/url] .
medicinskaya tehnika_zqEi
26 Oct 25 at 7:06 pm
наркологическая услуга москва [url=http://narkologicheskaya-klinika-24.ru]http://narkologicheskaya-klinika-24.ru[/url] .
narkologicheskaya klinika_ydSr
26 Oct 25 at 7:07 pm
Борьба с профессиональная дезинфекция удалась, фирма молодцы.
уничтожение блох
KennethceM
26 Oct 25 at 7:08 pm
https://herengezondheid.com/# officiele Sildenafil webshop
Hermanereli
26 Oct 25 at 7:09 pm
comprar Sildenafilo sin receta: Viagra genérico online España – Confia Farmacia
Jesuskax
26 Oct 25 at 7:11 pm
диплом купить колледжа [url=https://frei-diplom10.ru/]https://frei-diplom10.ru/[/url] .
Diplomi_ndEa
26 Oct 25 at 7:11 pm
кракен зеркало
кракен android
Henryamerb
26 Oct 25 at 7:11 pm
1xbetgiri? [url=https://1xbet-17.com/]1xbetgiri?[/url] .
1xbet_qhpl
26 Oct 25 at 7:12 pm
Как купить Фенибут в Венёве?Как считаете про https://tulaposuda.ru
? Цены нормальные, быстрая доставка. Кто-то покупал? Как на самом деле с качеством?
Stevenref
26 Oct 25 at 7:13 pm
поставщик медоборудования [url=www.medoborudovanie-postavka.ru/]www.medoborudovanie-postavka.ru/[/url] .
postavka medicinskogo oborydovaniya_xusn
26 Oct 25 at 7:14 pm
медицинская техника [url=medicinskaya-tehnika.ru]медицинская техника[/url] .
medicinskaya tehnika_kfEi
26 Oct 25 at 7:14 pm
Ukrainian President Volodymyr Zelensky condemned Russian attacks on the Ukrainian regions of Kharkiv, Zaporizhzhia and Sumy on Monday, saying that the Kremlin intends to “humiliate diplomatic efforts” just hours before European leaders visit the White House.
[url=https://kra-41-at.com]kra36 at[/url]
“The Russian war machine continues to destroy lives despite everything,” Zelensky said in a statement, hours before he’s due to meet US President Donald Trump in the Oval Office. “That is precisely why we are seeking assistance to put an end to the killings. That is why reliable security guarantees are required. That is why Russia should not be rewarded for its participation in this war.”
[url=https://kra-42—at.ru]kra36[/url]
“Everyone seeks dignified peace and true security,” the Ukrainian president said. “And at this very moment, the Russians are attacking Kharkiv, Zaporizhzhia, the Sumy region, and Odesa, destroying residential buildings and our civilian infrastructure.”
[url=https://kra—41cc.ru]kra37 cc[/url]
At least seven people were killed in Russia’s attack? on Kharkiv and a further three killed in the ballistic missile strike on the city of Zaporizhzhia, with scores more injured, according to Ukrainian authorities.
[url=https://kra41-cc.com]kra37 cc[/url]
“This was a demonstrative and cynical Russian strike,” Zelensky added.
kra42
https://kra-42—cc.ru
Ronniefluem
26 Oct 25 at 7:15 pm
kraken vk3
кракен официальный сайт
Henryamerb
26 Oct 25 at 7:17 pm
кракен Москва
kraken vpn
JamesDaync
26 Oct 25 at 7:18 pm
Thank you for the good writeup. It in fact used to be a leisure account it.
Glance complex to far brought agreeable from you!
However, how could we keep up a correspondence?
buka situs bokep
26 Oct 25 at 7:20 pm
1xbet tr giri? [url=http://www.1xbet-17.com]http://www.1xbet-17.com[/url] .
1xbet_yopl
26 Oct 25 at 7:21 pm
центр наркологии москва [url=narkologicheskaya-klinika-23.ru]narkologicheskaya-klinika-23.ru[/url] .
narkologicheskaya klinika_aiet
26 Oct 25 at 7:22 pm
поставка медицинского оборудования [url=http://medoborudovanie-postavka.ru]поставка медицинского оборудования[/url] .
postavka medicinskogo oborydovaniya_ohsn
26 Oct 25 at 7:24 pm
ShopForHappiness – Easy navigation, site layout makes shopping smooth and enjoyable overall.
Kim Muther
26 Oct 25 at 7:24 pm
1 xbet giri? [url=https://1xbet-14.com/]1xbet-14.com[/url] .
1xbet_ywet
26 Oct 25 at 7:26 pm
kraken vk6
kraken сайт
Henryamerb
26 Oct 25 at 7:26 pm
kraken tor
кракен онион
Henryamerb
26 Oct 25 at 7:27 pm
Поделитесь отзывами о дезинфекция после потопа! Как качество и цена?
уничтожение клопов
KennethceM
26 Oct 25 at 7:28 pm
Нужна обработка от клещей с гарантией, посоветуйте компанию.
санитарная обработка
KennethceM
26 Oct 25 at 7:30 pm
Ukrainian President Volodymyr Zelensky condemned Russian attacks on the Ukrainian regions of Kharkiv, Zaporizhzhia and Sumy on Monday, saying that the Kremlin intends to “humiliate diplomatic efforts” just hours before European leaders visit the White House.
[url=https://kra-42-cc.net]kra35 cc[/url]
“The Russian war machine continues to destroy lives despite everything,” Zelensky said in a statement, hours before he’s due to meet US President Donald Trump in the Oval Office. “That is precisely why we are seeking assistance to put an end to the killings. That is why reliable security guarantees are required. That is why Russia should not be rewarded for its participation in this war.”
[url=https://kra-41–cc.ru]kra41[/url]
“Everyone seeks dignified peace and true security,” the Ukrainian president said. “And at this very moment, the Russians are attacking Kharkiv, Zaporizhzhia, the Sumy region, and Odesa, destroying residential buildings and our civilian infrastructure.”
At least seven people were killed in Russia’s attack? on Kharkiv and a further three killed in the ballistic missile strike on the city of Zaporizhzhia, with scores more injured, according to Ukrainian authorities.
“This was a demonstrative and cynical Russian strike,” Zelensky added.
kra36 at
https://kra-41cc.com
Jamessew
26 Oct 25 at 7:31 pm
1x bet giri? [url=https://1xbet-14.com]1x bet giri?[/url] .
1xbet_npet
26 Oct 25 at 7:31 pm
pillole per disfunzione erettile: miglior sito per acquistare Sildenafil online – Viagra generico con pagamento sicuro
Jesuskax
26 Oct 25 at 7:31 pm
кракен маркетплейс
кракен клиент
Henryamerb
26 Oct 25 at 7:31 pm
Hello! This is my first visit to your blog! We are a group of volunteers and starting a
new initiative in a community in the same niche.
Your blog provided us beneficial information to work on. You have done a wonderful job!
kush casino зеркало
26 Oct 25 at 7:32 pm
поставщик медицинского оборудования [url=https://medoborudovanie-postavka.ru/]поставщик медицинского оборудования[/url] .
postavka medicinskogo oborydovaniya_lbsn
26 Oct 25 at 7:32 pm
В шляпных коробках «Флорион» раскрывает цветы как ювелирные миниатюры: гармоничные сочетания роз, орхидей, эустомы и гортензии выглядят современно и безупречно держат форму. Удобная подача, продуманная палитра и авторские названия композиций помогают точно передать эмоцию, а заказать легко на https://www.florion.ru/catalog/cvety-v-shlyapnoy-korobke — от лаконичных боксов до эффектных премиум-версий. Доставка по Москве и внимательная сборка — как в лучших ателье флористики.
gokenamFab
26 Oct 25 at 7:33 pm
поставка медицинского оборудования [url=https://medoborudovanie-postavka.ru]поставка медицинского оборудования[/url] .
postavka medicinskogo oborydovaniya_pmsn
26 Oct 25 at 7:34 pm
We’re a group of volunteers and opening a new scheme in our community.
Your site offered us with valuable info to work on. You have done a formidable job and
our entire community will be thankful to you.
ankara kürtaj
26 Oct 25 at 7:34 pm
kraken ссылка
kraken
JamesDaync
26 Oct 25 at 7:34 pm
1xbet g?ncel giri? [url=www.1xbet-17.com/]1xbet g?ncel giri?[/url] .
1xbet_hdpl
26 Oct 25 at 7:34 pm
dreamcreateinspire – The concept “Dream-Create-Inspire” resonates nicely for personal growth or creative content, which is a plus.
Gena Skalski
26 Oct 25 at 7:38 pm
реабилитационный центр наркологический [url=https://narkologicheskaya-klinika-23.ru/]narkologicheskaya-klinika-23.ru[/url] .
narkologicheskaya klinika_nuet
26 Oct 25 at 7:39 pm
поставщик медицинского оборудования [url=www.medoborudovanie-postavka.ru/]поставщик медицинского оборудования[/url] .
postavka medicinskogo oborydovaniya_stsn
26 Oct 25 at 7:40 pm
Ukrainian President Volodymyr Zelensky condemned Russian attacks on the Ukrainian regions of Kharkiv, Zaporizhzhia and Sumy on Monday, saying that the Kremlin intends to “humiliate diplomatic efforts” just hours before European leaders visit the White House.
[url=https://kra–42—at.ru]kra39[/url]
“The Russian war machine continues to destroy lives despite everything,” Zelensky said in a statement, hours before he’s due to meet US President Donald Trump in the Oval Office. “That is precisely why we are seeking assistance to put an end to the killings. That is why reliable security guarantees are required. That is why Russia should not be rewarded for its participation in this war.”
[url=https://kra-42.ru]kra41 at[/url]
“Everyone seeks dignified peace and true security,” the Ukrainian president said. “And at this very moment, the Russians are attacking Kharkiv, Zaporizhzhia, the Sumy region, and Odesa, destroying residential buildings and our civilian infrastructure.”
At least seven people were killed in Russia’s attack? on Kharkiv and a further three killed in the ballistic missile strike on the city of Zaporizhzhia, with scores more injured, according to Ukrainian authorities.
“This was a demonstrative and cynical Russian strike,” Zelensky added.
kra37 cc
https://kra-41—at.ru
Kennethtip
26 Oct 25 at 7:41 pm
Whats up very cool site!! Guy .. Excellent .. Wonderful ..
I will bookmark your blog and take the feeds additionally?
I’m glad to seek out numerous helpful information right here
in the post, we need develop more techniques on this regard, thank you for sharing.
. . . . .
filtered cat water bowl
26 Oct 25 at 7:41 pm
Hello, of course this post is in fact good and I have learned lot of
things from it about blogging. thanks.
turkey visa for australians
26 Oct 25 at 7:41 pm
куплю диплом медсестры в москве [url=http://www.frei-diplom15.ru]куплю диплом медсестры в москве[/url] .
Diplomi_lsoi
26 Oct 25 at 7:42 pm
медицинская техника [url=medicinskaya-tehnika.ru]медицинская техника[/url] .
medicinskaya tehnika_hbEi
26 Oct 25 at 7:42 pm
I like the helpful info you provide in your
articles. I will bookmark your blog and check again here regularly.
I’m quite certain I’ll learn many new stuff right here!
Good luck for the next!
AYUTOGEL
26 Oct 25 at 7:43 pm
1 xbet giri? [url=https://1xbet-17.com]1 xbet giri?[/url] .
1xbet_zqpl
26 Oct 25 at 7:43 pm
Отзывы о уничтожение вредителей положительные, попробуем.
травля тараканов
KennethceM
26 Oct 25 at 7:43 pm