This module enables you to build a living style guide based on Fractal components using the Twig templating language. It can either be used as a Drupal module or as a standalone Twig extension.

1. Consistency: Respect component definitions.

   The default variables of a component are read from its component definition file (usually *.config.yml).

   The class name of a component (or a variant of it) is not manually passed to the template each time it is used. Instead, every usage of the component ensures that that at least the component's class names are output (which should follow BEM).

   {% render '@atoms/button.twig' with { name: 'submit' } %}
   
   {% render '@atoms/button--primary.twig' with { label: 'Save' } %}
   
   {% render [
     '@pages/section--trythis.twig',
     '@pages/section--alternative.twig',
     '@pages/section.twig',
   ] %} 

   By design, the class name of a component or variant cannot be removed, it may only be amended.

2. Structure: Drupal Attributes.

   Any template context variable with "attributes" in its name is treated as a Drupal Attributes object. Use them intuitively in your Fractal components.

   context:
     attributes:
       class: article--teaser
     title: Dummy article title
     title_attributes:
       class: article__heading

   <article{{ attributes }}>
     <h1{{ title_attributes }}>{{ title }}</h1>
   </article>

3. Variance: Modifiers. Multiple modifiers.

   A variant is identified by its modifier name, as specified in the referenced component name:

   {% render '@atoms/button--primary.twig' %}

   This will look up the variant identified by modifier 'primary' in the 'button' atom:

   context:
     attributes:
       class: button
   
   variants:
     - modifier: primary
       context:
         label: Save
         attributes:
           class: button--primary

   Components may appear in multiple variations and states.

   {% render '@atoms/button--primary--disabled.twig' with { label: 'Save' } %}

Add the following in your project composer.json file:

composer config repositories.twig_fractal git https://github.com/netzstrategen/twig_fractal.git

composer require drupal/twig_fractal:dev-master

Drupal Core did not split its components into separate repositories yet, so the files need to be retrieved manually from the main repository. As soon as separate repositories for Drupal Components and Core become available, you can try to use them instead.

1. As the extension relies on some Drupal functionalities we need to grab the necessary files and autoload them:

   composer config repositories.drupal-attributes git https://github.com/netzstrategen/drupal-attributes.git
   
   composer require netzstrategen/drupal-attributes:dev-master

2. Register the Twig extension in your project:

   // Add 'render' tag for pattern library components.
   $twig->addExtension(new \Drupal\twig_fractal\TwigFractal());
   

https://github.com/netzstrategen/twig_fractal (this package) adds support for the {% render %} tag to the Twig environment in PHP (of your application).

https://github.com/netzstrategen/fractal-twig adds support for the {% render %} tag to the Twig environment in JavaScript (of the Fractal UI).