PHP 返回引用 - '&'来电者有必要吗? [英] PHP returning references - '&' necessary in caller?

问题描述

我正在使用 joomla 并且我已经阅读了 API，我注意到 JFactory 类有函数返回对对象的引用，但我从互联网收集的示例没有使用 & 使用功能时.

I'm using joomla and i have read through the API and I noticed the JFactory class having functions return a reference to the object but the examples I have gathered from the internet do not use the & when using the functions.

例如 Jfactory::getSession() 返回对全局会话的引用.文档 显示其定义为 function &getSession(params){code} - 明确定义引用返回.然而，在这个例子中，他们将其称为 $session = JFactory::getSession(); 不应该是 $session =&JFactory::getSession();?

Say for example the Jfactory::getSession() which returns a reference to the global session. the documentation shows that its defined as function &getSession(params){code} - clearly defining a reference return. however, in this example, they call it as $session = JFactory::getSession(); shouldn't it be $session =& JFactory::getSession();?

它在 php 文档 中指出，有一个 <函数中的 code>& 和调用者中的 =& .我也学过 C 编程，如果我错过了这样的事情，就会出现无效指针转换"之类的错误——这不是一个好的编程习惯.

It states here in the php documentation that there is an & in the function and an =& in the caller. I have also gone through C programming and if I miss things like this, there will be errors like "invalid pointer conversion" - which is not a good programming practice to tolerate.

正确的做法是什么?

附加信息:

我使用 joomla 1.7 并且我正在创建一个组件.我在 xampp 上使用 php 5.3.8

i use joomla 1.7 and i'm creating a component. i work on xampp with php 5.3.8

推荐答案

这取决于:
- Joomla 的版本和您使用的 PHP 版本
- 返回 JFactory::getSession() 方法的内容

It depends on:
- the version of Joomla and the version of PHP you use
- what returns the JFactory::getSession() method

Joomla 1.5 版本兼容 PHP 4 和 PHP 5，1.6 和 1.7 版本仅兼容 PHP 5.

Joomla version 1.5 is compatible with PHP 4 and PHP 5, versions 1.6 and 1.7 are only compatible with PHP 5.

如果该方法返回一个对象，& 在 PHP 4 中是强制性的:默认情况下，对象按值传递/返回(对象的副本发生).& 避免了复制.
在 PHP 5 中，& 是无用的:对象总​​是通过引用传递/返回(不发生复制).

If the method returns an object, the & is mandatory in PHP 4: by default, objects are passed/returned by value (a copy of the object occurs). The & avoids the copy.
In PHP 5, the & is useless : objects are always passed/returned by reference (no copy occurs).

如果该方法返回任何其他内容，则不应使用 & 但在某些非常罕见的情况下可能很有用(为了节省内存，如果您有一个巨大的数组或字符串，例如例如，您不想在作业中复制它们).

If the method returns anything else, the & shouldn't be used but can be useful in some very rare cases (in order to save memory if you have a huge array or string, for example, and you don't want of copy of them in the assignment).

当方法签名也包含 & 时，好的做法是始终将 & 放在赋值中.

The good practice is to always put a & in assignment when the method signature includes a & too.

就您而言，我认为您使用的是 PHP 5 和最新版本的 Joomla，所以不要使用 & :这可能是 Joomla 源代码中的过时代码.

In your case, I think that you're using PHP 5 and a recent version of Joomla, so don't use & : this is probably an obsolete code in Joomla sources.

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