筛选\'comments_open\' 检查它发生在同名函数内部，该函数在主题中调用，通常如下所示：

comments_open() and comment_form(
    array (
        \'comment_notes_after\' => \'\'
    )
);

add_filter( \'comments_open\', \'wpse_98775_comment_check\', 10, 2 ); 

function wpse_98775_comment_check( $open, $post_id )
{
    if ( $open )
        return $open;

    if ( \'my_post_type\' === get_post_type( $post_id ) )
        return TRUE;

    return $open;
}