Twig instanceof for inheritance objects

Question

I am using the following feature from propel http://www.propelorm.org/documentation/09-inheritance.html.

I am also using Symfony2 and Twig

I have a class structure using the above feature that looks something like this

class Event {}

class Birthday extends Event {}

class Walking extends Event {}

now I pass an event object to a twig template and I want to know what type of event it is

For instance I want to display an image of a cake if its a birthday and I want to display map routes if its walking event.

I cannot use instanceof in Twig as this feature does not exist. Does anyone now why this does not exist? and is there a way I can replicate this functionality without having to do something like

 public function getType()

in each class, or

 public function isBirthday()

in the event class.

I found this on github but it is of no use to me. I have commented on their to see if I can get an answer.

https://github.com/fabpot/Twig/issues/553

Answer 1

I share the opinion, that instanceof is nothing that should appear in a template. I use twig-tests for this case

class MyTwigExtension extends TwigExtension
{
    public function getTests ()
    {
        return [
            new \Twig_SimpleTest('birthday', function (Event $event) { return $event instanceof Birthday; }),
            new \Twig_SimpleTest('walking', function (Event $event) { return $event instanceof Walking; })
        ];
    }
}

And in the template

{% if event is birthday %}{# do something #}{% endif %}