public function getBySlug($sSlug, $bOnlySelectable = false)
    {
        $aAvailable = $this->getAll($bOnlySelectable);

        foreach ($aAvailable as $oType) {

            if ($oType->slug == $sSlug) {

                if (!isset($oType->instance)) {
                    $oType->instance = Factory::factory(
                        $oType->component,
                        $oType->provider
                    );
                }

                return $oType->instance;
            }
        }

        return null;
    }