How to do a PHP hook system?

You can build an events system as simple or complex as you want it.

/** * Attach (or remove) multiple callbacks to an event and trigger those callbacks when that event is called. * * @param string $event name * @param mixed $value the optional value to pass to each callback * @param mixed $callback the method or function to call - FALSE to remove all callbacks for event */function event($event, $value = NULL, $callback = NULL){    static $events;    // Adding or removing a callback?    if($callback !== NULL)    {        if($callback)        {            $events[$event][] = $callback;        }        else        {            unset($events[$event]);        }    }    elseif(isset($events[$event])) // Fire a callback    {        foreach($events[$event] as $function)        {            $value = call_user_func($function, $value);        }        return $value;    }}

Add an event

event('filter_text', NULL, function($text) { return htmlspecialchars($text); });// add more as neededevent('filter_text', NULL, function($text) { return nl2br($text); });// OR like this//event('filter_text', NULL, 'nl2br');

Then call it like this

$text = event('filter_text', $_POST['text']);

Or remove all callbacks for that event like this

event('filter_text', null, false);

Here's another solution:

Creating a hook

Run this wherever you want to create a hook:

x_do_action('header_scripts');

Attach a function to the hook

Then attach a function to the above by doing:

x_add_action('header_scripts','my_function_attach_header_scripts');function my_function_attach_header_scripts($values) {   /* add my scripts here */}

Global variable to store all hooks/events

Add this to the top of your main PHP functions file, or equivalent

$x_events = array();global $x_events;

Base functions

function x_do_action($hook, $value = NULL) {    global $x_events;    if (isset($x_events[$hook])) {        foreach($x_events[$hook] as $function) {            if (function_exists($function)) { call_user_func($function, $value); }        }    }}function x_add_action($hook, $func, $val = NULL) {    global $x_events;    $x_events[$hook][] = $func;}

this solutions has some problems that you can't set several function for one callable hook.you can fallow this code.

 $action = []; function apply($hook, $args){    global $action;    $action[$hook]['args'] = $args;    return doa($hook, $args); } function add($hook, $func){    global $action;    $action[$hook]['funcs'][] = $func; } function doa($hook,$args){    global $action;    if(isset($action[$hook]['funcs'])){        foreach($action[$hook]['funcs'] as $k => $func){            call_user_func_array($func, $args);       }    }     } add('this_is', 'addOne');function addOne($user){    echo "this is test add one $user <br>";}add('this_is', function(){    echo 'this is test add two <br>';});add('this_is_2', 'addTwo');function addTwo($user, $name){    echo $user . '   ' . $name . '<br>';}function test(){    echo 'hello one <br>';    apply('this_is', ['user'=> 123]);}function test2(){    echo 'hello two <br>';    apply('this_is_2', ['user'=> 123, 'name' => 'mohammad']);}test();test2();