变量处理顺序:PHP 7 中的变化 [英] Variable variables handling order: changes in PHP 7
问题描述
随着新的 PHP 7.0.0 的发布，我有点担心所谓的变量"的评估顺序的变化.
With the new PHP 7.0.0 out now, I'm a bit worried about the changes in evaluation order of the so-called 'variable variables'.
在此页面上，在对变量处理的更改"下有一个表格显示了表达式示例及其在 PHP 5 和 PHP 7 中的处理顺序.列出的四个表达式是:
On this page, under 'Changes to variable handling', a table is displayed with examples of expressions with their handling order in PHP 5 and PHP 7. The four expressions listed are:
$$foo['bar']['baz']
$foo->$bar['baz']
$foo->$bar['baz']()
Foo::$bar['baz']()
给定以下字符串和数组:
Given the following string and array:
$qux = 'quux';
$foo = array('bar' => array('baz' => 'qux'));
$$foo['bar']['baz'] 表中的第一个表达式在 PHP 5 中被解释为一个名为 $foo 中的值的变量的值['bar']['baz']，即$qux的值，即'quux'.
the first expression in the table $$foo['bar']['baz'] is interpreted in PHP 5 as the value of a variable named as the value in $foo['bar']['baz'], thus the value of $qux, which is 'quux'.
但是，据我了解，在 PHP 7 中，相同的表达式将被解释为一个名为 $foo 中的值的变量，因此我希望 PHP 通知将array to string"转换'，因为 $foo 是一个数组.
However, in PHP 7, as I understand it, the same expression will be interpreted as a variable named as the value in $foo, thus I expect a PHP Notice for an 'array to string conversion', since $foo is an array.
表中的其他示例似乎是同一主题的变体.
The other examples in the table seem to be a variation of this same theme.
当然，我很好奇为什么 PHP 7 会对此进行更改(具体来说，为什么此更改比向后兼容更重要)，但是，这对于 SO 来说不是一个合适的问题.我的问题更实际:
Of course I'm curious to why this is changed in PHP 7 (specifically, why is this change more important than being backwards compatible), however, that's not a suitable question for SO. My question is more practical:
应对这种不兼容性的推荐方法是什么?
当然，在有问题的表达式中添加花括号会有所帮助 (${$foo['bar']['baz']}, $foo->{$bar['baz']}、$foo->{$bar['baz']}() 和 Foo::{$bar['baz']}())，但是这样很麻烦，要翻很多旧代码，搜索的次数比较少……
Of course, adding curly braces to the offending expressions will help (${$foo['bar']['baz']}, $foo->{$bar['baz']}, $foo->{$bar['baz']}() and Foo::{$bar['baz']}()), but this is very cumbersome, going through tons of old code, searching for relatively few occurances...
否则，这四个示例是唯一可能的语法变化吗?也就是说，我可以创建一个 RegExp 和 grep 所有有问题的代码吗?可能存在哪些其他变体?
Otherwise, are these four examples the only possible syntax variations? That is, can I create a RegExp and grep all offending code? What other variations might exist?
推荐答案
Rasmus Lerdorf 编写了一个静态分析工具，可以发现这些所谓的统一变量语法问题，称为 Phan https://github.com/etsy/phan
Rasmus Lerdorf wrote a static analysis tool that can spot these so-called Uniform Variable Syntax issues, called Phan https://github.com/etsy/phan
Phan 有选项 -b, --backward-compatibility-checks 来检查潜在的 PHP 5 -> PHP 7 BC 问题.
Phan has the option -b, --backward-compatibility-checks to check for potential PHP 5 -> PHP 7 BC issues.
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