Add modules and themes as twig namespaces

Here is a initial patch. I don't know how to write a test for this, so maybe someone could help

@dmouse and @jmolivas have done some (as far as I know) related work around this, maybe find them on IRC to share knowledge :)

https://github.com/hechoendrupal/slang/blob/master/lib/Drupal/slang/Plug...

Patch still applies.

I'm curious what testbot thinks here. That patch is small, but if it works wooo!

I love this as it would make the life much easier for people which try to integrate some bundles into drupal.

1. +++ b/core/lib/Drupal/Core/Template/TwigEnvironment.php
   @@ -36,6 +36,19 @@ public function __construct(\Twig_LoaderInterface $loader = NULL, $options = arr
   +    $namespaces = \Drupal::moduleHandler()->getModuleList();
   +    foreach (\Drupal::service('theme_handler')->listInfo() as $theme => $info) {
   

   It would be cool to inject these new dependencies.

2. +++ b/core/lib/Drupal/Core/Template/TwigEnvironment.php
   @@ -36,6 +36,19 @@ public function __construct(\Twig_LoaderInterface $loader = NULL, $options = arr
   +    foreach ($namespaces as $name => $filename) {
   +      $templatesDirectory = dirname($filename) . '/templates';
   +      if (file_exists($templatesDirectory)) {
   +        $loader->addPath($templatesDirectory, $name);
   +      }
   

   What do you think about allowing people to use templates outside of the "templates" directory

3. +++ b/core/modules/system/lib/Drupal/system/Tests/Theme/TwigNamespaceTest.php
   @@ -0,0 +1,66 @@
   +    // Enabled module
   +    $this->assertTwigTemplate($this->twig->resolveTemplate('@node/node.html.twig'), 'Found node.tpl.php in node module.');
   +
   +    // Enabled theme
   +    $this->assertTwigTemplate($this->twig->resolveTemplate('@bartik/page.html.twig'), 'Found page.html.twig in bartik theme.');
   ...
   +    $this->assertText('This line is from twig_namespace_a/templates/test.html.twig');
   +    $this->assertText('This line is from twig_namespace_b/templates/test.html.twig');
   

   It would be also cool to have a direct test which just checks which template is used, not passive like this.

2. Sure its possible but, we already enforce the templates folder for themes already. Take a look at drupal_find_theme_templates().

Interesting, I was not aware of that.

3. I am not sure what you mean. The first part of the tests does this already. We could remove the seconds part completely. Because this tests the twig language/syntax and not the actual namespaces.

I agree this is enough test coverage.

Updated to fix two very minor nitpicks (below). I'd argue that this could be changed to a task, it will especially be useful for subthemes. Thanks for this @webflo and @chr.fritsch!

1. +++ b/core/modules/system/lib/Drupal/system/Tests/Theme/TwigNamespaceTest.php
   @@ -0,0 +1,66 @@
   +    $this->assertTwigTemplate($this->twig->resolveTemplate('@node/node.html.twig'), 'Found node.tpl.php in node module.');
   

   Should be .html.twig instead of .tpl.php.

2. +++ b/core/lib/Drupal/Core/Template/TwigEnvironment.php
   @@ -32,10 +34,23 @@ class TwigEnvironment extends \Twig_Environment {
   +    // Set twig path namespace for themes and modules
   

   Missing period per https://drupal.org/node/1354#drupal.

More docs updates and minor changes. The only material change is getting rid of a call to theme() in the tests, see #2173655: Refactor theme() to _theme(); make it a private API to discourage module developers from circumventing the renderable build system. I probably should have just made this a patch review, hope you don't mind @webflo :)

Edit: Interdiff is from #11.

Fine!

Wow! That syntax is definitely much nicer.

While this is sorta feature-y, it's also required to finalize the Twig API, so changing to a task.

Committed and pushed to 8.x. Thanks!

This is awesome. When we get #1308152: Add stream wrappers to access extension files in, we should probably change this format to use the stream wrapper syntax and just pass the path to be resolved by those.

I can't seem to get this working:

{% extends "@at_core/block.html.twig" %}

This just prints that out where the content should be.

Trying to change the branding block to extend my block.html.twig, both templates are in the base theme /templates directory, but of course my default active theme is a sub theme.

OK, the problem is clear - you can't have templates in sub directories:

adaptivetheme/at_core/templates/block/block.html.twig will not work.

Probably something to look at in #2291449: Add Twig template inheritance based on the theme registry, enable adding Twig loaders ?

Leaving active for now, however this is a regression from D7.

With the theme registry loader you could just do {% extends "block.html.twig" %}, currently you'd have to add the 'block' directory {% extends "@at_core/block/block.html.twig" %}

This is because the namespace maps directly to the templates directory and nothing more.

I think your use case will be fixed by the theme registry loader so re-closing. Thanks!

Edited to expand code samples and add code tags.