Example of an auto-included plugin "controller" script.

add-meta.php

<?php
if ( class_exists( 'Sizeable_Person' ) ) :
 
    add_action( 'add_meta_boxes', 'szbl_mvc_example_add_meta_boxes' );
    
    function szbl_mvc_example_add_meta_boxes()
    {
        add_meta_box( 'szbl-mvc-person-meta', 'Additional Information', 'szbl_mvc_example_meta_output', Sizeable_Person::POST_TYPE_SLUG, 'normal', 'high' );        
    }
    
    function szbl_mvc_example_meta_output()
    {
        if ( file_exists( dirname( __FILE__ ) . '/views/meta.php' ) )
            include dirname( __FILE__ ) . '/views/meta.php';
    }
 
endif;