When writing a Twig Extension in Symfony, why must you provide a getName()?

Question

Here is the Symfony Guide to writing Twig Extensions: http://symfony.com/doc/current/cookbook/templating/twig_extension.html

Note it says to provide:

// src/AppBundle/Twig/AppExtension.php
namespace AppBundle\Twig;

class AppExtension extends \Twig_Extension
{
    public function getName()
    {
        return 'app_extension';
    }
}

Here is the Twig API: https://github.com/twigphp/Twig/blob/1.x/lib/Twig/Extension.php

There is no getName function() there.

So why do we have to provide one? What purpose does it serve?

Dan Mironis Dan Mironis · Accepted Answer · 2015-12-18T09:04:44

Look at Twig_ExtensionInterface, which Twig_Extension implements, getName() need to be implemented in your custom twig extension according to the interface.

According to twig documentation by folks at sensiolabs (link here):

To keep your extension class clean and lean, it can inherit from the built-in Twig_Extension class instead of implementing the whole interface. That way, you just need to implement the getName() method as the Twig_Extension provides empty implementations for all other methods.

The getName() method must return a unique identifier for your extension.

When writing a Twig Extension in Symfony, why must you provide a getName()?

3 Answers