TYPO3 Core

Unfortunately PHP emphasizes "weak" over "map" in their new PHP 8
data-structure \WeakMap. As a result it cannot be passed to other
functions that would enrich an existing \WeakMap - since objects
created in that function scope would not exist outside and thus
directly trigger garbage collection of \WeakMap.

As a substitute, \TYPO3\CMS\Core\Type\Map is introduce with has a
similar behavior and got an additional Map::fromEntries() factory.

Example:

$map = new \TYPO3\CMS\Core\Type\Map();
$key = new \stdClass();
$value = new \stdClass();
$map[$key] = $value;

foreach ($map as $key => $value) { ... }

• example of \WeakMap draw-backs: https://3v4l.org/TSO37#v8.1.16
• example of \SplObjectStorage draw-backs with foreach: https://3v4l.org/gloDO#v8.1.16