Simple class for organizing and registering your WordPress shortcodes.

Shortcodes.php

<?php

namespace App;

class Shortcodes {

    protected $shortcodes = [];

    public function __construct()
    {
        $this->addShortcode('card');
    }

    private function addShortcode( $name )
    {
        $this->shortcodes[] = $name;
    }

    public function card( $atts , $content = null )
    {
        // Attributes
        $atts = shortcode_atts(
            array(
            ),
            $atts,
            'card'
        );

        $html = '<div class="card">';
        $html .= $content;
        $html .= '</div>';

        return $html;
    }

    public function register()
    {
        /**
         * Add the shortcodes
         */
        add_action( 'init', function() {
            foreach( $this->shortcodes as $name ) {
                add_shortcode( $name, [$this, $name] );
            }
        });
    }
}

/**
 * Register Shortcodes
 */
$shortcodes = new Shortcodes;
$shortcodes->register();