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!
купить диплом в луцке [url=https://educ-ua5.ru/]https://educ-ua5.ru/[/url] .
Diplomi_fiKl
17 Sep 25 at 9:46 am
купить диплом магистра украины [url=http://www.educ-ua20.ru]купить диплом магистра украины[/url] .
Diplomi_luEn
17 Sep 25 at 9:46 am
купить аттестат за 11 класс 2015 [url=www.arus-diplom25.ru/]купить аттестат за 11 класс 2015[/url] .
Diplomi_jhot
17 Sep 25 at 9:46 am
Приобрести диплом о высшем образовании!
Мы предлагаембыстро и выгодно приобрести диплом, который выполняется на оригинальном бланке и заверен мокрыми печатями, штампами, подписями. Диплом способен пройти лубую проверку, даже при использовании специальных приборов. Достигайте свои цели быстро и просто с нашей компанией- [url=http://notebooks.ru/forum/user/171402/]notebooks.ru/forum/user/171402[/url]
Jariorzek
17 Sep 25 at 9:48 am
There’s definately a lot to learn about this subject.
I love all of the points you made.
Aqua Tower
17 Sep 25 at 9:48 am
проект перепланировки нежилого помещения стоимость [url=www.pereplanirovka-nezhilogo-pomeshcheniya3.ru/]www.pereplanirovka-nezhilogo-pomeshcheniya3.ru/[/url] .
pereplanirovka nejilogo pomesheniya_pasa
17 Sep 25 at 9:50 am
Мы предлагаем документы университетов, которые расположены в любом регионе РФ. Купить диплом о высшем образовании:
[url=http://forum.artinvestment.ru/member.php?u=1807451/]купить аттестаты за 11 класс в санкт петербурге[/url]
Diplomi_shPn
17 Sep 25 at 9:50 am
https://fm88.football/
FM88
17 Sep 25 at 9:51 am
Right here is the perfect site for everyone who really wants to understand this topic.
You realize a whole lot its almost hard to argue with you (not that I actually will need to…HaHa).
You certainly put a new spin on a subject that’s been discussed for years.
Excellent stuff, just excellent!
turkey visa for australian
17 Sep 25 at 9:51 am
купить диплом о высшем образовании с реестром [url=www.arus-diplom33.ru/]купить диплом о высшем образовании с реестром[/url] .
Diplomi_agSa
17 Sep 25 at 9:51 am
согласование проекта перепланировки нежилого помещения [url=https://pereplanirovka-nezhilogo-pomeshcheniya1.ru/]https://pereplanirovka-nezhilogo-pomeshcheniya1.ru/[/url] .
pereplanirovka nejilogo pomesheniya_lxsi
17 Sep 25 at 9:52 am
купить диплом специалиста дешево [url=http://www.educ-ua17.ru]купить диплом специалиста дешево[/url] .
Diplomi_phSl
17 Sep 25 at 9:53 am
перепланировка в нежилом помещении [url=www.pereplanirovka-nezhilogo-pomeshcheniya3.ru]перепланировка в нежилом помещении[/url] .
pereplanirovka nejilogo pomesheniya_zbsa
17 Sep 25 at 9:53 am
где можно купить диплом [url=http://educ-ua4.ru]где можно купить диплом[/url] .
Diplomi_jwPl
17 Sep 25 at 9:54 am
Приобрести MEFEDRON MEF SHISHK1 GASH MSK
Да шляпа какая-то, менеджер работает из рук вон плохо, и валит все на курьера. Абсолютная неразбериха, понять, кто и в каком месте накосячил достоверно – просто невозможно, но тем не менее, факт остается фактом: больше недели я ожидаю отправку заказа, и это только отправка, причем, разумеется, с полной предоплатой. Общались с манагером через скайп и через аську, очень муторно, сообщения теряются, на оставленные мессаги в оффлайне не отвечает, да и в онлайне появляется довольно редко.
KennethImire
17 Sep 25 at 9:54 am
Заказать диплом любого университета!
Наши специалисты предлагаютвыгодно и быстро купить диплом, который выполнен на оригинальной бумаге и заверен печатями, водяными знаками, подписями официальных лиц. Документ способен пройти лубую проверку, даже при использовании специфических приборов. Решите свои задачи максимально быстро с нашей компанией- [url=http://vsbg.info/read-blog/7178/]vsbg.info/read-blog/7178[/url]
Jariorccn
17 Sep 25 at 9:54 am
Эта познавательная публикация погружает вас в море интересного контента, который быстро захватит ваше внимание. Мы рассмотрим важные аспекты темы и предоставим вам уникальные Insights и полезные сведения для дальнейшего изучения.
Кликни и узнай всё! – https://infinitebatteries.co.uk/hello-world
RussellSnums
17 Sep 25 at 9:54 am
I’ve been browsing online more than three hours today, yet
I never found any interesting article like yours. It is pretty
worth enough for me. Personally, if all website
owners and bloggers made good content as you did,
the net will be a lot more useful than ever before.
https://github.com/Roblox-Executor-Pc/pc-executor
17 Sep 25 at 9:56 am
купить диплом с занесением в реестры [url=http://educ-ua13.ru]купить диплом с занесением в реестры[/url] .
Diplomi_xupn
17 Sep 25 at 9:56 am
фильмы в хорошем качестве [url=https://kinogo-11.top/]https://kinogo-11.top/[/url] .
kinogo_ajMa
17 Sep 25 at 9:57 am
порядок согласования перепланировки нежилого помещения [url=www.pereplanirovka-nezhilogo-pomeshcheniya3.ru/]www.pereplanirovka-nezhilogo-pomeshcheniya3.ru/[/url] .
pereplanirovka nejilogo pomesheniya_zgsa
17 Sep 25 at 9:57 am
Мы предлагаем документы институтов, расположенных в любом регионе России. Заказать диплом любого ВУЗа:
[url=http://bezone.ru/node/360248/]купить аттестат за 11 классов москва[/url]
Diplomi_jxPn
17 Sep 25 at 9:58 am
internet apotheke: generika potenzmittel online bestellen – europa apotheke
Israelpaync
17 Sep 25 at 9:59 am
согласование перепланировки нежилого помещения [url=www.pereplanirovka-nezhilogo-pomeshcheniya1.ru]www.pereplanirovka-nezhilogo-pomeshcheniya1.ru[/url] .
pereplanirovka nejilogo pomesheniya_mpsi
17 Sep 25 at 9:59 am
gГјnstigste online apotheke [url=https://blaukraftde.com/#]Blau Kraft[/url] gГјnstigste online apotheke
StevenTilia
17 Sep 25 at 9:59 am
купить диплом вуза в киеве [url=https://educ-ua17.ru/]https://educ-ua17.ru/[/url] .
Diplomi_usSl
17 Sep 25 at 10:00 am
Hello, i think that i saw you visited my site so i came to return the want?.I’m attempting to in finding things to improve my website!I
suppose its good enough to make use of some of your concepts!!
pink salt for weight loss
17 Sep 25 at 10:00 am
ставки на спорт бишкек [url=https://www.mostbet12014.ru]https://www.mostbet12014.ru[/url]
mostbet_vdKl
17 Sep 25 at 10:01 am
смотреть фильмы бесплатно [url=http://www.kinogo-11.top]http://www.kinogo-11.top[/url] .
kinogo_paMa
17 Sep 25 at 10:01 am
где можно купить диплом [url=www.educ-ua4.ru]где можно купить диплом[/url] .
Diplomi_sgPl
17 Sep 25 at 10:02 am
Tourists fined and banned from Venice for swimming in canal
[url=https://trip-scan.co]трип скан[/url]
A couple from the United Kingdom had to cut their vacation in Venice short after being caught swimming in the Grand Canal.
The 35-year-old British man and his 25-year-old Romanian girlfriend were forced to return to their home in the UK on Thursday, the same day they arrived in the city, after gondoliers reported them to local police for taking a dip in the canal.
The pair were fined €450 ($529) each and expelled from Venice for 48 hours, marking the 1,136th such sanction to be handed down to badly behaved tourists in the city so far this year, according to the Venice City Police.
The unnamed couple took the plunge near the Accademia bridge near St. Mark’s Square and gondoliers at the Rio San Vidal kiosk immediately called authorities, who removed them from the water.
“I thank the gondoliers for their cooperation and timely reporting,” said Venice Security Councillor Elisabetta Pesce in a statement published by city authorities on Friday.
https://trip-scan.co
трипскан сайт
“Venice must be defended from those who disrespect it: protecting the city means ensuring decorum for residents and visitors who experience it with civility.”
Swimming in the Venice canals is prohibited for a variety of reasons, including the intense boat traffic and the cleanliness — or lack thereof — of the water, according to the city’s tourism ministry.
Of the 1,136 orders of expulsion from the city so far this year, about 10 were for swimming.
Related article
Tourists take photographs on the Rialto Bridge in Venice, Italy, on Saturday, April 8, 2023. Italy’s upcoming budget outlook will probably incorporate a higher growth forecast for 2023 followed by a worsened outlook for subsequent years, according to people familiar with the matter. Photographer: Andrea Merola/Bloomberg via Getty Images
Rising waters and overtourism are killing Venice. Now the fight is on to save its soul
“Since the beginning of the year, we have issued a total of 1,136 orders of expulsion for incidents of degradation and uncivilized behavior,” Venice local police deputy commander Gianni Franzoi said in a statement shared with CNN.
Poor visitor behavior is one of the worst byproducts of overtourism, Franzoi said, and incidents are on the rise.
In July 2024, an Australian man was fined and expelled for diving off the Rialto Bridge after his friends posted about it on social media.
The year before, two French tourists were fined and expelled for skinny dipping in the canal under the moonlight. In August 2022, a German man was fined and expelled for surfing in the canal.
Related article
Aerial view of the plagued ghost island of Poveglia in the Venetian lagoon
‘Haunted’ Venice island to become a locals-only haven where tourists are banned
Venice’s authorities have been trying to balance the need for visitor income with residents’ demands for a city that works for them.
Day trippers now pay a €10 entrance fee on summer weekends and during busy periods throughout the year.
The city has also banned tour groups of more than 25 people, loudspeakers and megaphones, and even standing on narrow streets to listen to tour guides.
“It was necessary to establish a system of penalties that would effectively deter potential violations,” Pesce said when the ordinance was passed in February.
“Our goal remains to combat all forms of irregularities related to overtourism in the historic lagoon city center,” she added.
“The new rules for groups accompanied by guides encourage a more sustainable form of tourism, while also ensuring greater protection and safety in the city and better balancing the needs of Venice residents and visitors.”
Brandonjex
17 Sep 25 at 10:02 am
купить диплом в хмельницком [url=https://www.educ-ua2.ru]https://www.educ-ua2.ru[/url] .
Diplomi_jyOt
17 Sep 25 at 10:02 am
купить диплом техникума недорого [url=educ-ua7.ru]купить диплом техникума недорого[/url] .
Diplomi_lgEr
17 Sep 25 at 10:03 am
переустройство и перепланировка нежилого помещения [url=pereplanirovka-nezhilogo-pomeshcheniya1.ru]pereplanirovka-nezhilogo-pomeshcheniya1.ru[/url] .
pereplanirovka nejilogo pomesheniya_ensi
17 Sep 25 at 10:03 am
купить диплом училища [url=http://educ-ua6.ru]купить диплом училища[/url] .
Diplomi_gzMl
17 Sep 25 at 10:03 am
купить диплом сколько [url=https://educ-ua17.ru/]купить диплом сколько[/url] .
Diplomi_tiSl
17 Sep 25 at 10:06 am
купить диплом института высшего образования [url=www.educ-ua20.ru]купить диплом института высшего образования[/url] .
Diplomi_fdEn
17 Sep 25 at 10:06 am
купить диплом в днепропетровске [url=http://educ-ua5.ru/]купить диплом в днепропетровске[/url] .
Diplomi_zrKl
17 Sep 25 at 10:06 am
This is really interesting, You’re a very skilled blogger.
I’ve joined your rss feed and look forward to seeking more of your wonderful post.
Also, I’ve shared your site in my social networks!
Liv Pure Reviews
17 Sep 25 at 10:07 am
порядок согласования перепланировки нежилого помещения [url=http://pereplanirovka-nezhilogo-pomeshcheniya1.ru]http://pereplanirovka-nezhilogo-pomeshcheniya1.ru[/url] .
pereplanirovka nejilogo pomesheniya_ausi
17 Sep 25 at 10:07 am
купить диплом о среднем образовании цена [url=http://www.educ-ua4.ru]купить диплом о среднем образовании цена[/url] .
Diplomi_xsPl
17 Sep 25 at 10:08 am
купить диплом с занесением в реестр в мурманске [url=http://arus-diplom33.ru]купить диплом с занесением в реестр в мурманске[/url] .
Diplomi_jrSa
17 Sep 25 at 10:09 am
микрозаймы онлайн [url=http://zaimy-11.ru/]http://zaimy-11.ru/[/url] .
zaimi_cyPt
17 Sep 25 at 10:09 am
Купить диплом любого университета!
Наша компания предлагаетбыстро купить диплом, который выполнен на оригинальном бланке и заверен мокрыми печатями, штампами, подписями официальных лиц. Наш диплом пройдет любые проверки, даже при помощи специальных приборов. Решайте свои задачи максимально быстро с нашей компанией- [url=http://zawayasyria.com/author/shawnanevarez/]zawayasyria.com/author/shawnanevarez[/url]
Jariorajj
17 Sep 25 at 10:10 am
смотреть сериалы новинки [url=https://kinogo-11.top/]https://kinogo-11.top/[/url] .
kinogo_jcMa
17 Sep 25 at 10:11 am
фильмы про войну смотреть онлайн [url=kinogo-15.top]фильмы про войну смотреть онлайн[/url] .
kinogo_ubsa
17 Sep 25 at 10:12 am
You would possibly already know that masturbation is super vital for understanding your vulva and getting used to completely different sensations.
FREE VIAGRA
17 Sep 25 at 10:12 am
bs2best at, bs2web at и bs2 market: глубокий анализ технологий 2025 года
bs2best at
bs2best.at blacksprut marketplace Official
CharlesNarry
17 Sep 25 at 10:14 am
купить аттестат в красноярске за 11 [url=http://arus-diplom25.ru/]купить аттестат в красноярске за 11[/url] .
Diplomi_bwot
17 Sep 25 at 10:14 am
купить свидетельство о разводе [url=https://educ-ua5.ru]https://educ-ua5.ru[/url] .
Diplomi_bwKl
17 Sep 25 at 10:14 am