Online PHP editor | output for I5phk

<?php class ImmutableClass { public function __construct( public readonly OtherClass $readonly_property, ) {} } class OtherClass { public function __construct( public int $foo = 0, public ?string $bar = null, ) {} } $object = new OtherClass(); $object->foo = 500; $immutable_object = new ImmutableClass(readonly_property: $object); var_dump($immutable_object->readonly_property); $immutable_object->readonly_property->foo = 100; $immutable_object->readonly_property->bar = 'oops'; var_dump($immutable_object->readonly_property);