Issue description

Recently, I had issue with auto-load in my custom extension using JLoader::registerPrefix:

I have a MVC library which has prefix OS. OSController, OSModel.... So I register that prefix using this code:

JLoader::registerPrefix('OS', PATH_TO_LIBRARY_FOLDER);

My component has the name com_osmembership and I want my controllers, models, views.... to be auto-loading as well, so I register another prefix:

JLoader::registerPrefix('OSMembership', PATH_TO_MY_COMPONENT);

The problem happens when Joomla tries to load a class in my component, for example OSMembershipController. Joomla sees that this class started with OS, so It tries to find that class from PATH_TO_LIBRARY_FOLDER as starting point for finding. Of course, it could not found the class and result class not found error. As you can see, I expect that Joomla will find that class from PATH_TO_MY_COMPONENT. If Joomla does that, it will find the class and won't return class not found error.

So the question is: Is this a bug ? or I am using it in a wrong way?

Possible solution:

If we agree that this is a bug, I think we can modify the code of _autoload. The idea is looping over all the registered prefix until we found a class. The change code is:

    private static function c($class)
    {
        foreach (self::$prefixes as $prefix => $lookup)
        {
            $chr = strlen($prefix) < strlen($class) ? $class[strlen($prefix)] : 0;
            if (strpos($class, $prefix) === 0 && ($chr === strtoupper($chr)))
            {
                $found =  self::_load(substr($class, strlen($prefix)), $lookup);
                if ($found !== false)
                {
                    return $found;
                }
            }
        }

        return false;
    }

That code solve the issue but will make the system loop few more times, not sure it will cause any performance issue?