How to use the is_active_sidebar hook from within a widget class?

Hello,

I have a custom widget in a theme that in some cases (conditionally) returns false in its widget() method, i.e. no HTML output.

The widget area is checked with is_active_sidebar() (the function) before displaying the widgets and wrapping HTML.

Now, if there is a widget that outputs nothing, is_active_sidebar() is still TRUE because there IS a widget in the sidebar and the wrapping HTML is displayed (an empty aside for example).

I have a hacky solution with output buffering the widget area and checking if the string is empty.

As of WordPress 3.9. I found there is a new hook is_active_sidebar (not the function) to manipulate is_active_sidebar() (the function). I would like to use this in the custom widget’s widget() method to set is_active_sidebar to FALSE when the widget returns false / outputs nothing, like the following, but it doesn’t work. How would I go about it?

function widget( $args, $instance ) {
        extract( $args );

        if ( $custom_condition ) {
            add_filter( 'is_active_sidebar', '__return_false');
            return false;
        }

        [...]

        /* Output widget HTML. */
        echo $output;
    }