Worpress Plugin: Calls the action 'save_post' for Attachment Post Types. Requires PHP 5.3

dna-save-attachment.php

<?php
/**
 * Plugin Name: dna Save Attachment
 * Plugin URI:  https://gist.github.com/4214994
 * Author:      David Naber
 * Author URI:  http://dnaber.de/
 * Version:     2014.08.24
 * Description: Calls the action 'save_post' for Attachment Post Types vor WordPress versions prior 4.0. Requires PHP 5.3. The plugin will have no effect in WordPress 4.0 or higher. (Getting obsolete when <a href="http://core.trac.wordpress.org/ticket/21963">#21963</a> is fixed.)
 */
namespace DNA\SaveAttachment;

/**
 * calls the action 'save_post'
 * will be no longer neccessary when http://core.trac.wordpress.org/ticket/21963 gets solved.
 *
 * @wp-hook edit_attachment
 * @wp-hook add_attachment
 * @param int $post_ID
 * @return void
 */
function do_save_post( $post_ID ) {

	if ( ! version_compare( $GLOBALS[ 'wp_version' ], '4.0-beta', 'lt' ) )
		return;

	$post = get_post( $post_ID );
	if ( ! $post )
		return;

	do_action( 'save_post', $post_ID, $post );
}
add_action( 'edit_attachment', __NAMESPACE__ . '\do_save_post', 5, 1 );
add_action( 'add_attachment',  __NAMESPACE__ . '\do_save_post', 5, 1 );