Wrap meta boxes & data handling for specific post types in classes?

Question

I have a site with a few custom post types, each with their own custom data, meta boxes & assets (stylesheets, images, JavaScript).

Typically I'd hook onto add_meta_boxes to register all my meta boxes and save_post to handle the data, but in this case I'd like to wrap all the functionality for each post type in a class & abstract out the process of instantiation.

My proposal is as follows;

function my_prefix_admin_load_post()
{
    /* Grab current post type - can't use global $post_type since it isn't set yet! */
    if ( isset( $_GET['post'] ) )
        $post_type = get_post_type( $_GET['post'] );
    elseif ( isset( $_REQUEST['post_type'] ) )
        $post_type = basename( $_REQUEST['post_type'] );
    else
        $post_type = 'post';

    /* Construct classname & filename from post type. */
    $post_type_file = dirname( __FILE__ ) . "/inc/class-post-$post_type.php";
    $post_type_class = 'Class_Prefix_' . ucfirst( $post_type );

    if ( is_file( $post_type_file ) )
        require $post_type_file;

    if ( class_exists( $post_type_class ) )
        new $post_type_class;
}
add_action( 'load-post.php', 'my_prefix_admin_load_post' );
add_action( 'lost-post-new.php', 'my_prefix_admin_load_post' );

This way, I can drop in enhancements for a new or existing post type at anytime (without tinkering with my base functions), and without code for different post types intermingling with another.

However, I can't help but feel the loading process is just a little... icky. I'd really love to hear of suggestions, whether improvements or alternate approaches!

Answer 1

Not really a complete answer, but since this question's become a ghost town I thought it was worth adding.

$post_type = get_current_screen()->id; // when on post.php or post-new.php

It's been around for a while, but with 3.3's much improved screen API I can see this opening a new world of easier, on-demand loading.