TODO
====

Currently the `FeatureManager` class is a very shallow interpretation of Piotr Miazga's proposed
API and associated scaffolding classes (see https://phabricator.wikimedia.org/T244481 and
https://gerrit.wikimedia.org/r/#/c/mediawiki/skins/Vector/+/572323/). This document aims to list
the steps required to get from this system to something as powerful as Piotr's.

1. ~~Decide whether "set" is the correct name~~
2. Add support for sets that utilise contextual information that isn't available at boot time, e.g.

```php
use Vector\Constants;
use IContextSource;

$featureManager->registerRequirement( Constants::LOGGED_IN_REQ, function( IContextSource $context ) {
	$user = $context->getUser();

	return $user
		&& $user->isSafeToLoad()
		&& $user->isLoggedIn();
} );

$featureManager->registerRequirement( Constants::MAINSPACE_REQ, function ( IContextSource $context ) {
	$title = $context->getTitle();

	return $title && $title->inNamespace( NS_MAIN );
} );
```

3. Consider supporing memoization of those requirements (see https://gerrit.wikimedia.org/r/#/c/mediawiki/skins/Vector/+/573626/7/includes/FeatureManagement/FeatureManager.php@68)
4. Add support for getting all requirements
5. Add support for getting all features enabled when a requirement is enabled/disabled