How to install a Twig extension How do install a Twig extension in Craft? Not write my own extension, but install an extension that exists. I want to install the extensions extension. There are a number of posts that describe how to write your own extension, but I can't see how to just install one. The Twig docs says add this: $twig-&gt;addExtension(new Twig_Extensions_Extension_Array()); but obviously I don't want to edit core Craft. 

I found this - How do you add a core twig extension in plugins using addTwigExtension()?, but the responses just convince the poster that he doesn't need to use that extension. What if he wanted to use it? How do you install it?
The BreakAndContinue plugin is an example of a plugin that adds a simple twig extension. I would start with that, and modify it to add the extensions extension (I assume that is this: https://github.com/twigphp/Twig-extensions ?) You might need to tweak the Twig PHP to get files to load etc., but not core Craft, since this will be a plugin.