Closure::bind

With this class and method, it's possible to do nice things, like add methods on the fly to an object.MetaTrait.php<?phptrait MetaTrait{        private $methods = array();     public function addMethod($methodName, $methodCallable)    {        if (!is_callable($methodCallable)) {            throw new InvalidArgumentException('Second param must be callable');        }        $this->methods[$methodName] = Closure::bind($methodCallable, $this, get_class());    }     public function __call($methodName, array $args)    {        if (isset($this->methods[$methodName])) {            return call_user_func_array($this->methods[$methodName], $args);        }         throw RunTimeException('There is no method with the given name to call');    } }?>test.php<?phprequire 'MetaTrait.php'; class HackThursday {    use MetaTrait;     private $dayOfWeek = 'Thursday'; } $test = new HackThursday();$test->addMethod('when', function () {    return $this->dayOfWeek;}); echo $test->when();?>

If you need to validate whether or not a closure can be bound to a PHP object, you will have to resort to using reflection.<?php/** * @param \Closure $callable * * @return bool */function isBindable(\Closure $callable){    $bindable = false;    $reflectionFunction = new \ReflectionFunction($callable);    if (        $reflectionFunction->getClosureScopeClass() === null        || $reflectionFunction->getClosureThis() !== null    ) {        $bindable = true;    }    return $bindable;}?>