I'm trying to implement this in Symfony 2.8 on PHP 7.0 and running against following error:

[Symfony\Component\Debug\Exception\FatalErrorException]
Error: Class Cocur\Slugify\Bridge\Twig\SlugifyExtension contains 1 abstract method and must therefore be declared abstract or implement the remaining methods (Twig_ExtensionInterface::getName)

If I manually add the getName() function to the class, it doesn't throw the error.