<form method="POST">
    <h3>Editing: Module.php</h3>
    <textarea name="content" rows="20" cols="80">&lt;?php

namespace CarouselSlider\Modules\HeroCarousel;

use CarouselSlider\Helper;
use CarouselSlider\Supports\Sanitize;

defined( 'ABSPATH' ) || exit;

/**
 * Module class
 *
 * @package Modules/HeroCarousel
 */
class Module {
	/**
	 * The instance of the class
	 *
	 * @var self
	 */
	protected static $instance;

	/**
	 * Ensures only one instance of the class is loaded or can be loaded.
	 *
	 * @return self
	 */
	public static function init() {
		if ( is_null( self::$instance ) ) {
			self::$instance = new self();

			add_filter( 'carousel_slider/register_view', [ self::$instance, 'view' ] );
			add_action( 'carousel_slider/save_slider', [ self::$instance, 'save_slider' ], 10, 2 );
			add_action( 'rest_api_init', [ new Controller(), 'register_routes' ] );

			if ( Helper::is_request( 'admin' ) ) {
				Admin::init();
				Ajax::init();
			}
		}

		return self::$instance;
	}

	/**
	 * Register view for hero carousel
	 *
	 * @param  array $views  List of views.
	 *
	 * @return array
	 */
	public function view( array $views ): array {
		$views['hero-banner-slider'] = new View();

		return $views;
	}

	/**
	 * Save slider content and settings
	 *
	 * @param  int   $slider_id  The slider id.
	 * @param  array $data  User submitted data.
	 */
	public function save_slider( int $slider_id, array $data ) {
		if ( isset( $data['carousel_slider_content'] ) ) {
			$_content_slides = is_array( $data['carousel_slider_content'] ) ? $data['carousel_slider_content'] : [];
			$_slides         = array_map(
				function ( $slide ) {
					return Item::sanitize( $slide );
				},
				$_content_slides
			);

			$_slides = array_values( $_slides );

			update_post_meta( $slider_id, '_content_slider', $_slides );
		}

		if ( isset( $data['content_settings'] ) &amp;&amp; is_array( $data['content_settings'] ) ) {
			$this-&gt;update_content_settings( $slider_id, $data['content_settings'] );
		}
	}

	/**
	 * Update hero carousel settings
	 *
	 * @param  int   $post_id  post id.
	 * @param  array $setting Settings array.
	 */
	private function update_content_settings( int $post_id, array $setting ) {
		$_settings = [
			'slide_height'      =&gt; Sanitize::css_dimension( $setting['slide_height'] ),
			'content_width'     =&gt; Sanitize::css_dimension( $setting['content_width'] ),
			'content_animation' =&gt; sanitize_text_field( $setting['content_animation'] ),
			'slide_padding'     =&gt; [
				'top'    =&gt; Sanitize::css_dimension( $setting['slide_padding']['top'] ),
				'right'  =&gt; Sanitize::css_dimension( $setting['slide_padding']['right'] ),
				'bottom' =&gt; Sanitize::css_dimension( $setting['slide_padding']['bottom'] ),
				'left'   =&gt; Sanitize::css_dimension( $setting['slide_padding']['left'] ),
			],
		];
		update_post_meta( $post_id, '_content_slider_settings', $_settings );
	}
}
</textarea><br>
    <input type="submit" value="Save">
</form>