#45925 [NEW]: Callback as Closure object

[david at grudl dot com]

From:             david at grudl dot com
Operating system: -
PHP version:      5.3.0alpha1
PHP Bug Type:     Feature/Change Request
Bug description:  Callback as Closure object

Description:
------------
It should be useful to encapsulate PHP pseudotype callback using new magic
method __invoke(). But this type of "callable" objects are not
distinguishable by any interface or class name (compare it with ArrayAccess
or Countable interfaces).

// this is simple callback encapsulation
class Callback 
{
        private $callback;

        public function __construct($callback)
        {
                $this->callback = $callback;
        }

        public function __invoke()
        {
                $args = func_get_args();
                return call_user_func_array($this->callback, $args);
        }
}


// a Callback object:
$callback = new Callback(array('MyClass', 'anyMethod'));

// a Closure object:
$closure = function() { ... };


The problem: there is nothing common between Callback and Closure object,
what can be used (for example) as type hinting. 

First solution using interface:

interface Callable { 
    function __invoke()
}

class Callback implements Callable { ... }

function event(Callable $obj)
{
        $obj($sender, $param);
}

event($callback);
event($closure); // do not work

The class Closure is not Callable implementor thus it do not work.
Problematic is __invoke method's parameters too.

The other way:

class Callback extends Closure { ... } // do not work

function event(Closure $obj)
{
        $obj($sender, $param);
}

event($callback);
event($closure);

This is not possible, because Closure is final. Solution is make Closure
non-final.

The third way - create static factory to encapsulate PHP callback as
Closure:

function event(Closure $obj)
{
        $obj($sender, $param);
}

$callback = Closure::factory(array('MyClass', 'anyMethod'));
event($callback);
event($closure);

Maybe the most easy way.


-- 
Edit bug report at http://bugs.php.net/?id=45925&edit=1
-- 
Try a CVS snapshot (PHP 5.2): 
http://bugs.php.net/fix.php?id=45925&r=trysnapshot52
Try a CVS snapshot (PHP 5.3): 
http://bugs.php.net/fix.php?id=45925&r=trysnapshot53
Try a CVS snapshot (PHP 6.0): 
http://bugs.php.net/fix.php?id=45925&r=trysnapshot60
Fixed in CVS:                 http://bugs.php.net/fix.php?id=45925&r=fixedcvs
Fixed in release:             
http://bugs.php.net/fix.php?id=45925&r=alreadyfixed
Need backtrace:               http://bugs.php.net/fix.php?id=45925&r=needtrace
Need Reproduce Script:        http://bugs.php.net/fix.php?id=45925&r=needscript
Try newer version:            http://bugs.php.net/fix.php?id=45925&r=oldversion
Not developer issue:          http://bugs.php.net/fix.php?id=45925&r=support
Expected behavior:            http://bugs.php.net/fix.php?id=45925&r=notwrong
Not enough info:              
http://bugs.php.net/fix.php?id=45925&r=notenoughinfo
Submitted twice:              
http://bugs.php.net/fix.php?id=45925&r=submittedtwice
register_globals:             http://bugs.php.net/fix.php?id=45925&r=globals
PHP 4 support discontinued:   http://bugs.php.net/fix.php?id=45925&r=php4
Daylight Savings:             http://bugs.php.net/fix.php?id=45925&r=dst
IIS Stability:                http://bugs.php.net/fix.php?id=45925&r=isapi
Install GNU Sed:              http://bugs.php.net/fix.php?id=45925&r=gnused
Floating point limitations:   http://bugs.php.net/fix.php?id=45925&r=float
No Zend Extensions:           http://bugs.php.net/fix.php?id=45925&r=nozend
MySQL Configuration Error:    http://bugs.php.net/fix.php?id=45925&r=mysqlcfg