php - 为什么我的变量会发生这种情况？

Question

<?php

// $searchResult is type of Outcome
// This is what we do:
dList::lessAnchor($searchResult)->showElement();
dList::moreAnchor($searchResult)->showElement();

/**
* @returns vAnchor (can get showed with showElement() - not part of the problem)
*/
public static function lessAnchor(Outcome $searchResult){
  $searchData = $searchResult->searchData;
  $searchData->Page = $searchData->Page - 1; // (!1)
  return self::basicAnchor($searchData, "Back");
}

/**
* @returns vAnchor (can get showed with showElement() - not part of the problem)
*/
public static function moreAnchor(Outcome $searchResult){
  $searchData=$searchResult->searchData;
  $searchData->Page = $searchData->Page + 1; // (!2)
  return self::basicAnchor($searchData, "More");
}

当我打电话时 dList::lessAnchor()在 $searchResult ，它修改了 $searchData->Page 的属性如您所见，将其减 1，标记为 (!1) .
过了一会儿(下面一行)，我调用 dList::moreAnchor()在 $searchResult再次。

为什么我看到 Page属性在 (!2) 处减少 1标记？我没有通过 $searchResult引用。

Answer 1

看看the documentation : 这是预期的行为。

As of PHP 5, an object variable doesn't contain the object itself as value anymore. It only contains an object identifier which allows object accessors to find the actual object. When an object is sent by argument, returned or assigned to another variable, the different variables are not aliases: they hold a copy of the identifier, which points to the same object.

如果你想避免这种情况，你应该 clone your object有需要的地方。就像这样:

public static function lessAnchor(Outcome $searchResult){
  $searchData = clone $newResult->searchData; //$searchData now is a new object
  $searchData->Page=$searchData->Page-1; // (!1)
  return self::basicAnchor($searchData,"Back");
}