protected function setCacheAlias($sAliasKey, $sOriginalKey)
    {
        if (!static::$CACHING_ENABLED) {
            return false;
        } elseif (empty($sAliasKey) || empty($sOriginalKey)) {
            return false;
        }

        $sOriginalCacheKey = $this->getCache($sOriginalKey, false);

        if (is_null($sOriginalCacheKey)) {
            return false;
        }

        $this->aCache[$sOriginalCacheKey]->key[] = $this->getCachePrefix() . $sAliasKey;
        $this->aCache[$sOriginalCacheKey]->key   = array_unique($this->aCache[$sOriginalCacheKey]->key);

        // --------------------------------------------------------------------------

        return true;
    }