my default bootstrap

bootstrap.php

<?php
session_start();

date_default_timezone_set ('America/Sao_Paulo');

define ('DS', DIRECTORY_SEPARATOR);
define ('URL', "http://".$_SERVER['SERVER_NAME']);
define ('ENVIRONMENT'  , 'DEV');

spl_autoload_register('autoload');

function autoload($className)
{
    $className = ltrim($className, '\\');
    $fileName  = '';
    $namespace = '';
    if ($lastNsPos = strripos($className, '\\')) {
        $namespace = substr($className, 0, $lastNsPos);
        $className = substr($className, $lastNsPos + 1);
        $fileName  = str_replace('\\', DIRECTORY_SEPARATOR, $namespace) . DIRECTORY_SEPARATOR;
    }
    $fileName .= str_replace('_', DIRECTORY_SEPARATOR, $className) . '.php';

    require $fileName;
}

if (ENVIRONMENT == 'DEV')
    error_reporting(E_ALL);
else
    error_reporting(0);