On his Mdeium.com site Pawel Mikolajczuk has written up a post showing you how to create a custom Twig node and parser to extend the powerful functionality already included in this popular PHP templating package.

If You want to create custom twig node then this tutorial is for You. I will show you step by step how to create custom twig syntax (DSL) called gimme (we build it for our Superdesk Publisher project).

He starts with the required changes to your composer.json file to pull Twig in and a sample index.php file to build the Twig instance and add in the new extension (the "gimmie" handling). He then provides the code needed to create the extension based on Twig_Extension for the new node type. Next is an example of the "gimmie" handling in action in a template, dumping out the user information when the article is requested. He explains what each part of the tag is doing and shares the code to create the parser for its contents. Finally he shares the code required to create the "node" class, converting it over to its parsed PHP equivalent.