We've switched from using Semantic Bundle to install extensions by using Composer. Now we can skip, for some extensions, manually including entry points at the LocalSettings.php file (http://www.bn2vs.com/blog/2013/11/24/introduction-to-composer-for-mediawiki-developers). But how does MediaWiki know which extensions to load. Does it read composer.json?
The answer, as stated in www.mediawiki.org/wiki/Composer:
Composer creates an autoloader at vendor/autoload.php, which is included by WebStart.php
I verified this - WebStart.php
simply does this:
# Load composer's autoloader if present
if ( is_readable( "$IP/vendor/autoload.php" ) ) {
require_once "$IP/vendor/autoload.php";
}