Hello @nikic. Good RFC. What about using closure inside and default variables?
Something like this
class Test {
private $url = 'https://some.com';
private $key = 'some-api-key';
private $client = new Client($this->url, $this->key);
private $lazyClient = static function () { return new Client()}; }

//or we can use anonymous class for this
public $lazyClient = new class { function __invoke() { return new Client()}; }

}

@nikic any chance of getting this in PHP 8.1? when does feature freeze start?

@zlianon Feature freeze is currently planned for Jul 20, see https://wiki.php.net/todo/php81.

Closing in favor of #7153.