php中对象的传递其实是值传递

https://www.tutorialspoint.com/how-do-you-pass-objects-by-reference-in-php-5

参考： https://www.cnblogs.com/aademeng/articles/9194688.html

This isn't "pass by reference". It actually is "assignment by reference". In PHP 5 assignment by reference is the default behaviour with objects.

A PHP reference is an alias, that allows two different variables to write it to the same value. In PHP version 5, an object variable doesn't contain the object itself as its value. It holds an object identifier that allows object accessors to find the actual object.

When an object is sent by an argument, returned or assigned to a different variable, these different variables are not aliases. They contain a copy of the identifier, that points to the same object

-----------------------------

<?php
class A {
  public $name = 'aa';
  public $age  = 13;
  public $b = null;
}

class B {
  public $name = 'aa';


}

$a = new A();
$b = $a;
$b = 123;
var_dump($a);
var_dump($b);