Method Calls with Arbitrary Names
#################################

:category:  PHP
:tags:
:date:      2020-07-24 07:20:00 +0300

A discovery of the day.
Many people know that you can define and read an object property with an arbitrary name:

.. code-block:: php

    <?php

    $s = new stdClass();
    $s->{'any string here'} = 123;
    echo $s->{'any string here'}; // 123

.. TEASER_END

This is useful from time to time when parsing json for example:

.. code-block:: php

    <?php

    $data = json_decode('{"any string here": 123}', false);
    echo $data->{'any string here'};

It's a more rare knowledge that you can also call methods with this syntax.
Probably because it's not usually useful, after all you cannot define a method with a name from an arbitrary string.
However you can catch such call with a magic method:

.. code-block:: php

    <?php

    class ClassWithCall
    {
        function __call($name, $arguments)
        {
            var_dump(func_get_args());
        }
    }

    $cc = new ClassWithCall();

    $cc->{"any string here"}(123); // 'any string here', [123]

    // also works with other indirect calls
    call_user_func([$cc, "any string here"], 123);
    $func = "any string here";
    $cc->$func();

It works in all versions of PHP after 5.0: https://3v4l.org/YCCE3, also with static context and ``__callStatic`` since 5.3.

I don't know if this trick has many uses but for example it looks good as a `Symfony EventSubscriber implementation <es_>`_.

.. _es: https://symfony.com/doc/current/components/event_dispatcher.html#using-event-subscribers

.. code-block:: php

    <?php

    use Psr\Container\ContainerInterface;
    use Symfony\Component\EventDispatcher\EventSubscriberInterface;

    class EventSubscriber implements EventSubscriberInterface
    {
        private ContainerInterface $container;

        public static function getSubscribedEvents()
        {
            return [
                SomeEvent::class => SomeListener::class,
            ];
        }

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

        public function __call(string $name, array $arguments): void
        {
            $listener = $this->container->get($name);
            $listener->onEvent($arguments[0]);
        }
    }