Filters can change an output or behavior of different parts of your theme or WordPress.
They should be defined inside app/Setup/filters.php
file. Inside you can see a standard example of modifying the length of the excerpt.
namespace Tonik\Theme\App\Setup;
function modify_excerpt_length()
{
return 60;
}
add_filter('excerpt_length', 'Tonik\Theme\App\Setup\modify_excerpt_length');
Examples
Using filters to control sidebar visibility
Controlling sidebar visibility is a great use case for custom filters. Let's start with creating markup of our sidebar inside filtered conditional.
<?php if (apply_filters('theme/sidebar/visibility', true)): ?>
<aside>
<?php get_sidebar() ?>
</aside>
<?php endif ?>
Create a filter which hides the sidebar on a page with 404 error view.
namespace Tonik\Theme\App\Setup;
function display_sidebar($status)
{
$conditions = [is_404(), is_page()];
if (in_array(true, $conditions)) {
return false;
}
return $status;
}
add_filter('theme/sidebar/visibility', 'Tonik\Theme\App\Setup\display_sidebar');