flush_widget_cache is deprecated. Which method should i use instead?

Question

The reviewer of my theme told me that flush_widget_cache() which I have used in one of my widgets is deprecated since version 4.4. I have searched for this method on codex but there is only a description that this function is deprecated and that's it.

Can anybody tell me that which method should i use instead of flush_widget_cache()?

Here is a code spinet from my widget (recent posts):

function update( $new_instance, $old_instance ) {
        $instance = $old_instance;
        $instance['title'] = strip_tags($new_instance['title']);
        $instance['number'] = (int) $new_instance['number'];
        $instance['show_date'] = (bool) $new_instance['show_date'];
        $this->flush_widget_cache();

        $alloptions = wp_cache_get( 'alloptions', 'options' );
        if ( isset($alloptions['widget_recent_entries']) )
            delete_option('widget_recent_entries');

        return $instance;
    }

    function flush_widget_cache() {
        wp_cache_delete('widget_recent_posts', 'widget');
    } 

Thanks.

Answer 1

The real question is why do you want to cache anything at all. If the widget is a common "recent posts" then all the practical object caching you are doing is mostly a duplication of the caching done in `WP_query' when you query for the posts. Or in other words, the simplest solution is to remove the caching related code.

Update

As @jami0821 pointed out in the comments, the latest version of the theme check tool removes that specific check, so you might ask the reviewer to make sure he uses the latest version. That said, there is still no reason to keep that code around.