WordPress: Shortcode for display Feed RSS

<?php
/*
 ********************************************************************************
 *                                                                              *
 * WordPress: Shortcode for display Feed RSS                    *
 * Author: Lucas S. B. Mastella <lucas[at]bello[dot]li>                         *
 * Site: http://bello.li/                           *
 * Date: 03/03/2012                                                             *
 *                                                                              *
 ********************************************************************************
 *                                                                              *
 *  Attribute:  URL, NUM, TARGET                        *
 *  Default: NUM=3, TARGET="blank"                      *
 *      num     = [0-9]^                        *
 *      target  = [blank, self, parent, top]                *
 *                                      *
 *  Ex.: [feed url="http://bello.li/feed/" num=5 target="self"]     *
 *                                                                              *
 ********************************************************************************
 *                                                                              *
 * This program is free software: you can redistribute it and/or modify         *
 * it under the terms of the GNU General Public License as published by         *
 * the Free Software Foundation, either version 3 of the License, or            *
 * (at your option) any later version.                                          *
 *                                                                              *
 * This program is distributed in the hope that it will be useful.              *
 * but WITHOUT ANY WARRANTY; without even the implied warranty of               *
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the                *
 * GNU General Public License for more details.                                 *
 *                                                                              *
 * You should have received a copy of the GNU General Public License            *
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.        *
 *                                                                              *
 ********************************************************************************
 *
 * Thank's to:
 * RSS Widget doesn’t update: http://newtotheweb.net/2009/10/25/rss-widget-doesnt-update/
 *
 */

function feed_fetcher( $atts ) {
    // Update Cache
    add_filter( 'wp_feed_cache_transient_lifetime', create_function( '$a', 'return 0;' ) );

    // Shortcode Attribute
    extract( shortcode_atts( array(
        'url' => '',
        'num' => '3',
        'target' => 'blank'
    ), $atts ) );

    // Fetch Feed
    include_once( ABSPATH . WPINC . '/feed.php' );
        $rss = fetch_feed( $url );
        $max = $rss->get_item_quantity( $num );
        $rss_itens = $rss->get_items( 0, $max );

        if ( $max == 0 ) echo 'No URL has been added!';
        else
            foreach ( $rss_itens as $item ) :
                echo '<a href="' . $item->get_permalink() . '" target="_' . $target . '">' . $item->get_title() . '</a><br />';
            endforeach;
}
add_shortcode( 'feed', 'feed_fetcher' );
?>