Modern PHP,
zero compromise.

function register_book_post_type() {
    register_post_type('book', [
        'labels' => [
            'name'          => 'Books',
            'singular_name' => 'Book',
            'add_new'       => 'Add New Book',
            'edit_item'     => 'Edit Book',
            'view_item'     => 'View Book',
        ],
        'public'       => true,
        'has_archive'  => true,
        'show_in_rest' => true,
        'supports'     => ['title', 'editor', 'thumbnail'],
    ]);
}
add_action('init', 'register_book_post_type');

use Pollora\Attributes\PostType;
use Pollora\Attributes\ShowInRest;

#[PostType('book')]
#[HasArchive]
#[Supports(['title', 'editor', 'thumbnail'])]
#[ShowInRest]
class Book {}

// Auto-discovered. Auto-registered.
// Labels generated from the class name.

// functions.php — action
add_action('init', 'setup_custom_rewrites', 20);

function setup_custom_rewrites() {
    add_rewrite_rule(/* ... */);
}

// functions.php — filter
add_filter('the_content', 'add_cta_to_posts');

function add_cta_to_posts($content) {
    if (is_single()) {
        $content .= '<div class="cta">...</div>';
    }
    return $content;
}

use Pollora\Attributes\Action;
use Pollora\Attributes\Filter;

class ContentHooks
{
    #[Action('init', priority: 20)]
    public function setupRewrites(): void
    {
        // Auto-discovered, auto-registered
    }

    #[Filter('the_content')]
    public function addCta(string $content): string
    {
        return $content . '<div class="cta">...</div>';
    }
}

// 1. Register custom 6h interval
add_filter('cron_schedules', function($s) {
    $s['every_6h'] = [
        'interval' => 21600,
        'display'  => 'Every 6 hours',
    ];
    return $s;
});

// 2. Schedule daily cleanup
if (!wp_next_scheduled('daily_cleanup')) {
    wp_schedule_event(time(), 'daily', 'daily_cleanup');
}
add_action('daily_cleanup', 'do_daily_cleanup');

function do_daily_cleanup() {
    // Clean up old data
}

// 3. Schedule feed check every 6h
if (!wp_next_scheduled('check_feeds')) {
    wp_schedule_event(time(), 'every_6h', 'check_feeds');
}
add_action('check_feeds', 'do_check_feeds');

function do_check_feeds() {
    // Check RSS feeds
}

use Pollora\Attributes\Schedule;
use Pollora\Schedule\Every;
use Pollora\Schedule\Interval;

class Maintenance
{
    #[Schedule(Every::DAY)]
    public function dailyCleanup(): void
    {
        // Runs daily. Auto-registered.
    }

    #[Schedule(new Interval(hours: 6))]
    public function checkFeeds(): void
    {
        // Custom interval. No cron_schedules filter.
    }
}