<?php

public function someController1($id)
{
	private $fileGateway;
	
	$file = $this->fileGateway->getFile($id);
	if (!isset($file)) {
		throw new notFoundException();
	}
}

public function someController2($id)
{
	private $fileGateway;
	
	try {
		$file = $this->fileGateway->getFile($id);
	} catch (Exception $e) {
		throw new notFoundException();
	}
}

public function someFileGateway1()
{
	public function getFile($id) {
		if (!$this->isFileExist($id)) {
			return null;
		}
	}
}

public function someFileGateway2()
{
	public function getFile($id) {
		if (!$this->isFileExist($id)) {
			throw new Exception();
		}
	}
}