Post numbering function for WordPress

post-numbers.php

<?php

/**
 * Display a post count on WordPress posts
 * Just use mw_post_number() inside the loop and you'll get a post number count
 * @author Matt Wiebe
 * @link http://somadesign.ca/
 * @license GPL v2 {@link} http://www.opensource.org/licenses/gpl-2.0.php
 * @copyright 2011
 */

class MW_Post_Numbers {
	
	private $count = 0;
	private $posts = array();
	
	public function display_count() {
		$this->init(); // doing it this way to prevent unnecessary queries
		$id = get_the_ID();
		echo sprintf( '<div class="post-counter"><span class="num">%s</span><span class="slash">/</span><span class="total">%s</span></div>', $this->posts[$id], $this->count );
	}
	
	private function init() {
		if ( $this->count )
			return;
		global $wpdb;		
		$posts = $wpdb->get_col( "SELECT ID FROM $wpdb->posts WHERE post_status = 'publish' AND post_type = 'post' ORDER BY post_date " );
		$this->count = count($posts);
		
		foreach ( $posts as $key => $value ) {
			$this->posts[$value] = $key + 1;
		}
		unset($posts);
	}
	
}
$GLOBALS['mw_post_numbers'] = new MW_Post_Numbers;

function mw_post_number() {
	$GLOBALS['mw_post_numbers']->display_count();
}