(PHP 5 >= 5.1.0, PHP 7, PHP 8)
SplSubject::attach — Attach an SplObserver
$observer
Attaches an SplObserver so that it can be notified of updates.
本函數還未編寫(xiě)文檔，僅有參數列表。
observer
The SplObserver to attach.
沒(méi)有返回值。