這種行為是完全正常的。事實(shí)上，如果您的屬性是對(duì)象（始終通過(guò)引用傳遞），您甚至不需要顯式創(chuàng)建引用：class Foo{    private Datetime $when;    public function __construct()    {        $this->when = new DateTime('1950-12-31');    }    public function getWhen(): DateTime    {        return $this->when;    }}$f = new Foo();$w = $f->getWhen();$w->modify('+50 years');var_dump($w, $f);object(DateTime)#2 (3) {  ["date"]=>  string(26) "2000-12-31 00:00:00.000000"  ["timezone_type"]=>  int(3)  ["timezone"]=>  string(13) "Europe/Madrid"}object(Foo)#1 (1) {  ["when":"Foo":private]=>  object(DateTime)#2 (3) {    ["date"]=>    string(26) "2000-12-31 00:00:00.000000"    ["timezone_type"]=>    int(3)    ["timezone"]=>    string(13) "Europe/Madrid"  }}這與您引用的文檔并不矛盾。該屬性本身無(wú)法訪問(wèn)：$f->when;// PHP Fatal error:  Uncaught Error: Cannot access private property Foo::$when參考文獻(xiàn)是一種不同的語(yǔ)言功能。也許通過(guò)另一個(gè)例子更容易理解：function a(){    $local_variable = 1;    b($local_variable);    echo "b modified a's local variable: $local_variable\n";}function b(&$number){    echo "b can read a's local variable: $number\n";    $number++;}a();b can read a's local variable: 1b modified a's local variable: 2