Recursively include all PHP files

require_all_helper.php

<?php

/**
     * Scan the api path, recursively including all PHP files
     *
     * @param string  $dir
     * @param int     $depth (optional)
     */
    protected function _require_all($dir, $depth=0) {
        if ($depth > $this->max_scan_depth) {
            return;
        }

        // require all php files
        $scan = glob("$dir/*");
        foreach ($scan as $path) {
            if (preg_match('/\.php$/', $path)) {
                require_once $path;
            }
            elseif (is_dir($path)) {
                $this->_require_all($path, $depth+1);
            }
        }
    }

Remember that the included PHP files would be in _require_all function context, so variables won't be accessible outside. (This doesn't mean that functions and classes won't work)