以下是对wp_tag_cloud() 功能：

function custom_wp_tag_cloud( $args = \'\' ) {
    $defaults = array(
        \'smallest\' => 8, \'largest\' => 22, \'unit\' => \'pt\', \'number\' => 45,
        \'format\' => \'flat\', \'separator\' => "\\n", \'orderby\' => \'name\', \'order\' => \'ASC\',
        \'exclude\' => \'\', \'include\' => \'\', \'link\' => \'view\', \'taxonomy\' => \'post_tag\', \'echo\' => true
    );
    $args = wp_parse_args( $args, $defaults );

    $tags = get_terms( $args[\'taxonomy\'], array_merge( $args, array( \'orderby\' => \'count\', \'order\' => \'DESC\' ) ) ); // Always query top tags

    if ( empty( $tags ) )
        return;

    foreach ( $tags as $key => $tag ) {
        if ( \'edit\' == $args[\'link\'] )
            $link = get_edit_tag_link( $tag->term_id, $tag->taxonomy );
        else
            $link = get_term_link( intval($tag->term_id), $tag->taxonomy );
        if ( is_wp_error( $link ) )
            return false;

        $tags[ $key ]->link = $link;
        $tags[ $key ]->id = $tag->term_id;
    }

    $return = wp_generate_tag_cloud( $tags, $args ); // Here\'s where those top tags get sorted according to $args

    $return = apply_filters( \'wp_tag_cloud\', $return, $args );

    if ( \'array\' == $args[\'format\'] || empty($args[\'echo\']) )
        return $return;

    echo $return;
}

$args = array(
   \'taxonomy\' => array( \'post_tag\', \'custom_taxonomy\' )
);
custom_wp_tag_cloud( $args );