使用三元运算符时可以通过引用传递吗? [英] Can you pass by reference while using the ternary operator?

问题描述

简单的问题，简单的代码.这有效:

Simple question, simple code. This works:

$x = &$_SESSION['foo'];

这不是:

$x = (isset($_SESSION['foo']))?&$_SESSION['foo']:false;

它抛出PHP Parse error: syntax error, unexpected '&'.使用条件运算符时是否只能通过引用传递引用，为什么不呢?如果?和&之间存在空格，也会发生这种情况.

It throws PHP Parse error: syntax error, unexpected '&'. Is it just not possible to pass by reference while using the conditional operator, and why not? Also happens if there's a space between the ? and &.

推荐答案

简单答案:否.如果要使用if/else，则必须走很长一段路.一次拥有一个引用，而下一次拥有一个值，这种情况也很罕见，并且可能会造成混淆.我会觉得这更直观，但是话又说回来，我当然不知道您的代码:

Simple answer: no. You'll have to take the long way around with if/else. It would also be rare and possibly confusing to have a reference one time, and a value the next. I would find this more intuitive, but then again I don't know your code of course:

if(!isset($_SESSION['foo'])) $_SESSION['foo'] = false;
$x = &$_SESSION['foo'];

原因:不知道，可能解析器必须在这一点上将某事物视为值的副本或引用的创建，而这种方式无法在解析时确定.

As to why: no idea, probably it has to with at which point the parser considers something to be an copy of value or creation of a reference, which in this way cannot be determined at the point of parsing.

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