Now that Drupal 9 has been released we can begin testing and experimenting with theming.  For those of us using Pattern Lab as a pattern library for component-based development, it’s a little more complex.  As you may already know, the largest difference from a theming standpoint between Drupal 8 and Drupal 9 is that the latter uses Twig version 2. This means two things:

  1. Your Twig files need to be purged of anything that was deprecated in Twig 1 and therefore no longer available in Twig 2.
  2. Your composer build must use Twig 2 and that all your packages must be ready to use that version. 

From the Drupal side Twig is already completely upgraded to version 2 in core, and many contrib modules as well. This is just not the case with Pattern Lab. In this talk, we'll go over some steps that we hope will ease your journey to getting your Pattern Lab integrated theme working in Drupal 9.

In this session we will ensure our pattern lab-based theme is compatible with twig 2.0.  Basic understanding of Pattern Lab and Twig is helpful for this talk.