PHP 8.0: New get_resource_id function

TypeNew Feature

PHP resources, such as Curl handlers, open files, database connections, can be cast to int. PHP 8 adds a new get_resource_id function that is essentially a (int) $resource cast to make it easier to retrieve the resource ID.

The advantage of the new get_resource_id function is the type safety, that arguments and return type are checked to be a resource and an int.

get_resource_id() Function synopsis

function get_resource_id($res): int {}

Note that PHP does not have a resource type that can be enforced yet.


function get_resource_id($res): int {
    if (!\is_resource($res) && null === @get_resource_type($res)) {
        throw new \TypeError(sprintf('Argument 1 passed to get_resource_id() must be of the type resource, %s given', get_debug_type($res)));

    return (int) $res;

From Symfony/Polyfill package. Supports PHP 7.0 and later.

Backwards Compatibility Impact

get_resource_id is a new function, and it can be easily polyfilled in previous PHP versions. Unless you have declared a function with exact same name in the global namespace, there should not be any problems.