Use your own Intl-Resources with ResourceBundle

Code
<?php

// Resources: http://bugs.icu-project.org/trac/browser/icu/trunk/source/data/curr
// res-files created with genrb
$resource __DIR__ '/resources';

// italian locale, returns null on error
$curr = new ResourceBundle('it'$resource);

// get old german currency
$demCurrency $curr->get('Currencies')
    ->
get('DEM');

echo 
$demCurrency->get(0) . PHP_EOL;
echo 
$demCurrency->get(1) . PHP_EOL;

// no error happened
echo 'ErrorCode: ' $curr->getErrorCode() .
    
', ErrorMessage: ' $curr->getErrorMessage();
Result
DEM
Marco Tedesco
ErrorCode: 0, ErrorMessage: U_ZERO_ERROR
Used Versions
PHP 7.1, Zend 3.0, Symfony 3.2, Laravel 5.2, PHPUnit 5.6, Doctrine 2.6