BasePostType.php

<?php

class BasePostType {

    protected $defaultArgs = array(
        'public' => true,
        'supports' => array(
            'title', 'editor', 'thumbnail' 
        ),
        'has_archive' => true
    );

    function __construct()
    {
        global $wpdb;
        $this->wpdb = $wpdb;

        $defaultArgs = array_filter($this->defaultArgs);
        $this->parsedArgs = wp_parse_args( $this->args, $defaultArgs );
        
        add_action( 'init', array( $this, 'register' ) );
    }

    function register()
    {
        register_post_type( $this->name, $this->parsedArgs );
    }

}

ExamplePostType.php

<?php

class ExamplePostType extends BasePostType
{

    protected $name = 'example';
    protected $args = array(
        'label' => 'Example',
        'rewrite' => array( 'slug' => 'example' ),
        'supports' => array( 'title', 'thumbnail' ),
        'menu_icon' => 'dashicons-images-alt',
        'taxonomies' => array('category'),
    );

    public function __construct()
    {
        parent::__construct();
    }

}

$example = new Example();