Calling closure assigned to object property directly

closures, object, php, properties

Solution

As of PHP7, you can do

$obj = new StdClass;
$obj->fn = function($arg) { return "Hello $arg"; };
echo ($obj->fn)('World');

or use Closure::call(), though that doesn't work on a `StdClass`.

Before PHP7, you'd have to implement the magic `__call` method to intercept the call and invoke the callback (which is not possible for `StdClass` of course, because you cannot add the `__call` method)

class Foo
{
    public function __call($method, $args)
    {
        if(is_callable(array($this, $method))) {
            return call_user_func_array($this->$method, $args);
        }
        // else throw exception
    }
}

$foo = new Foo;
$foo->cb = function($who) { return "Hello $who"; };
echo $foo->cb('World');

Note that you cannot do

return call_user_func_array(array($this, $method), $args);

in the `__call` body, because this would trigger `__call` in an infinite loop.

Problem

I would like to be able to call a closure that I assign to an object's property directly without reassigning the closure to a variable and then calling it. Is this possible? The code below doesn't work and causes `Fatal error: Call to undefined method stdClass::callback()`. ``` $obj = new stdClass(); $obj->callback = function() { print "HelloWorld!"; }; $obj->callback(); ```

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