CRM_Core_Resources - Allow container to swap the implementation

[totten]

Overview

CRM_Core_Resources manages the registration of page-level resources, such as JS and CSS files. This changes the construction logic so that it becomes possible for an extension to modify the definition of CRM_Core_Resources.

This is intended to allow experimentation with theme-management in extensions.

Before and After (Unchanged)

CRM_Core_Resources::singleton(), Civi::resources(), and Civi::container()->get('resources') all return the same object.

Before

The object construction is handled in the singleton() function.

After

The object construction is handled in the Container. Container defintions can be modified via hook_civicrm_container.

Technical Details

A possible critique: "You can't move everything in the container; is this one safe?." The main limitation of the container is that it cannot initialize boot-critical services (i.e. it's not available during pre/early-bootstrap). However, the resource manager is not boot-critical. You can tell this because the old logic (from CRM_Core_Resources::singleton()) already relied on having a working container (to lookup js_strings). If it was boot-critical, then the old call to Civi::cache('js_strings') would have been crash-y.

[civibot]

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[eileenmcnaughton]

@totten I'm happy to merge this at this stage - I feel like we have discussed & this will be part of any solution - although it may not be the only part. Do you have any reason I should hold off at this stage?

[totten]

@eileenmcnaughton Yes, I think it's fine to merge too.

Aside on r-run: Based on past experience, I was curious about resource handling in some oddball screens (like profiles embedded under Drupal's /user paths) -- but these seem to work as well as before (on both local and the autobuild demo).