Class Autoloader for WordPress theme

theme-autoloader.php

<?php namespace Potsdam\Inc;
/**
 * Potsdam Theme Autoloader
 *
 * @package Potsdam
 * @since 1.0
 */
/** No Direct Access */
if ( ! defined( 'ABSPATH' ) )
	die( 'Fizzle' );
/**
 * Class autoloader
 * @param  string $class fully qualified class name
 * @return null
 */
function autoloader( $class ) {
	$namespace_parts = explode( '\\', $class );
	$file_parts = array_map( __NAMESPACE__ . '\\convert_namespace_part_to_file_part', $namespace_parts);
	$file = get_theme_root() . '/' . implode( DIRECTORY_SEPARATOR, $file_parts ) . '.php';
	if ( file_exists( $file ) ) {
		require_once $file;
	}
}
spl_autoload_register( __NAMESPACE__ . '\\autoloader' );
/**
 * Convert namespace part to file part
 * @param  string $part namespace part
 * @return string       filename part
 */
function convert_namespace_part_to_file_part( $part ) {
	return str_replace( '_', '-', strtolower( $part ) );
}