public static function render()
{
$args = context::get_escaped(self::$alias);
foreach (self::$vars as $name => $value) {
// helper set 到 block 模板的变量都以下标开始
$args['_' . $name] = $value;
}
echo self::render_tpl('block/' . self::$block_name . '.tpl', $args, false);
}