<?php
define('TEMPLATES_DIR', 'templates');
///
abstract class Controller
{
	protected $m_templateName = 'default.tpl';

	public function template()
	{
		// Some actions
		ob_start();
		include(TEMPLATES_DIR . DIRECTORY_SEPARATOR . $this->m_templateName);
		$data = ob_get_contents();
		ob_clean();

		return $data;
	}
}

class Home extends Controller
{
	protected $m_templateName = 'home.tpl';
}

class Login extends Controller
{
	protected $m_templateName = 'login.tpl';
}

class Error404 extends Controller
{
	protected $m_templateName = 'error.tpl';
}
////

if (isset($_GET['page']))
{
	switch ($_GET['page'])
	{
		case 'home':
			$controller = new Home();
		case 'login':
			$controller = new Login();
			break;
		default:
			$controller = new Error404();
			break;
	}
}
else
	$controller = new Home();

echo $controller->template();

unset($controller);

define ('TEMPLATE', 'default') // Выбор шаблона