Php callback (e.g. jQuery)?

Question

in jQuery you can write something like

$(selector).bind('click', function(e) { // something was true - do these actions. }); 

I was wondering if in php you can do something like this without using eval.

something like that? I know this work does not work.

 class act{ public function bind($pref, $callback) { if($pref == 'something' ) { // return and perform actions in $callback? eval($callback); } } } 

Some of you may ask what is needed for this? Well, I'm trying to simplify my code without using so many if statements.

 $act = new act; $act->bind('something', function(e) { echo 'this was the php code to run in the callback'; }); 

The above code will not allow you to use a bunch of if statements.

 $act = new act; if( $act->bind('something') ) { // bind returned true so do this? } 

I know that you could use ob_get_contents to return the circled code, but ewww.

 ob_start(); eval('?> ' . $callback . '<?php '); $evaled = ob_get_contents(); ob_end_clean(); return $evaled; 

Answer 1

 if($pref == 'something' ) { // return and perform actions in $callback? call_user_func($callback); } 

call_user_func does what you want, you can even pass arguments

http://it.php.net/call_user_func

Example

 function g($msg,$func){ echo $msg; call_user_func($func); } g('hello',function (){echo 'hello2';}); // prints: hellohello2 

Answer 2

You really can define callback functions (or methods) in PHP.

This can be implemented using:

• call_user_func() and other familly functions
• Or anonymous functions , with PHP> = 5.3

In a few examples, consider the callback section on the next page of the manual: Pseudo-types and variables used in this documentation

Answer 3

If you pass multiple arguments to the callback, use call_user_func_array , like the already mentioned call_user_func , except for the second parameter, it takes an array of arguments.

 $functionName = 'foo'; $functionArgs = array('bar', 'baz'); call_user_func_array($functionName, $functionArgs); 

Alternatively, you can pass an anonymous function, not a function name.

 $functionBody = function($arg1, $arg2){ echo $arg1 . $arg2; }; $functionArgs = array('bar', 'baz'); call_user_func_array($functionBody, $functionArgs); 

An anonymous function can be passed as a variable, as in this example, or declared directly inline as an argument.

Answer 4

PHP 5.3 actually adds anonymous functions, so you can basically pass the function as an argument to another function call and execute it from there.

http://php.net/manual/en/functions.anonymous.php

 $callback = function($name){ printf("Hello %s\r\n", $name); }; $act->bind('test', $callback); 

Answer 5

The other answers are wonderful so far, but, seeing that your main interest in the events, I will show you how to do it, along with the chain (bonus!).

 /** * jQuery events+chaining prototype. */ class pQuery { /// PROTECTED PROPERTIES /// /** * @var array Holds list of event=>callbacks items. */ protected $events=array(); /// PROTECTED UTILITY METHODS /// /** * Creates an anonymous function compatible with PHP 4+. * <b>IMPORTANT</b> It is likely functions made this way are not garbage collected. * @param $funcCode string Function decleration, including the body. * @return string The newly created function name. */ protected static function mk_anonFunc($funcCode){ static $counter=0; $func='pQanon'.(++$counter); @eval('function '.$func.'('.substr($funcCode,9)); if(!function_exists($func)) die('Fatal: Anonymous function creation failed!'); return $func; } /** * Detects whether a string contains an anonymous function or not. * @param $funcCode string Function decleration, including the body. * @return boolean True if it does contain an anonymous function, false otherwise. */ protected static function is_anonFunc($funcCode){ return strpos($funcCode,'function(')!==false; } /// PUBLIC METHODS /// /** * Bind event callback to this jQuery instance. * @param string $event The event name, eg: 'click'. * @param string|array $callback A function or a class/instance method, eg: * 'myFunc' OR array('myClass','myMtd') OR array($obj,'myMtd'). * @return pQuery Chaining. */ public function bind($event,$callback){ if(self::is_anonFunc($callback)) $callback=self::mk_anonFunc($callback); if(!isset($this->events[$event])) $this->events[$event]=array(); $this->events[$event][]=$callback; return $this; } /** * Unbind event callback from this jQuery instance. * @param string $event The event name, eg: 'click'. * @param string|array $callback A function or a class/instance method, eg: * 'myFunc' OR array('myClass','myMtd') OR array($obj,'myMtd'). * @return pQuery Chaining. */ public function unbind($event,$callback){ if(!isset($this->events[$event])){ if(($pos=array_search($callback,$this->events[$event]))!==false) unset($this->events[$event][$pos]); } return $this; } /** * Trigger event, calling all related callbacks. * @param string $event The event name to trigger, eg: 'click'. * @param array $params Optional array of arguments to pass to callback. * @return pQuery Chaining. */ public function trigger($event,$params=array()){ if(isset($this->events[$event])) foreach($this->events[$event] as $callback) call_user_func_array($callback,$params); return $this; } } /** * Allows us to use factory-singleton pattern. * @return pQuery The $pQuery instance. */ function pQuery(){ global $pQuery; if(!isset($pQuery)) $pQuery=new pQuery(); return $pQuery; } 

And here is an example:

 // instantiate pQuery // Note: to use it like jQuery does, do it as follows // and then simply use "global $pQuery;" wherever you want it. $pQuery = new pQuery(); // declare some sample callbacks function start(){ echo 'start'; } function stop(){ echo 'stop'; } // bind some stuff and call start $pQuery->bind('start','start') ->bind('stop','stop') ->trigger('start'); // bind more stuff and call click $pQuery->bind('click','function(){ echo "clicked"; }') ->bind('custom','function(){ echo "custom"; }') ->bind('click','function(){ echo "clicked2"; }') ->trigger('click',array($pQuery,'arg2','arg3')); // call end $pQuery->trigger('stop');