PHP7在所有标准php函数中添加斜杠php-cs-fixer规则

Question

继承了PHP7项目。以前的开发人员甚至为\ true都对所有标准PHP函数添加了斜线。有什么理由吗？

一些例子：

\array_push($tags, 'master');

if ($result === \true) {}

$year = \date('Y');

切换此选项的php-cs-fixer规则是什么？

Answer 1

You can use the slash to make sure you are using the native PHP function or constant and not the function / constant with the same name defined in a namespace of the project.

namespace test;

function array_push($arr, $str) {
    return $str;
 }

$arr = [];

var_dump(array_push($arr, 'Hello World'));   // array_push defined in namespace test
var_dump(\array_push($arr, 'Hello World'));  // native array_push function

demo: https://ideone.com/3xoFhm

Another case why you can use the \ slash is to speed up the resolving (as mentioned on the PHP-CS-Fixer documentation). PHP doesn't need to use the autoloader to find the function or constant declaration. So with leading \ PHP can use native function without additional checks.

You can toggle this option on the PHP-CS-Fixer with the native_function_invocation (for functions) and native_constant_invocation (for constants) option. You can find an explanation of the options on the following page: https://github.com/FriendsOfPHP/PHP-CS-Fixer

Answer 2

As other answers have pointed out, prefixing global or built in functions and constants with \ makes sure they are not over-ridden by declarations within the current namespace. An alternative with the same effect is to add use function foo; and use constant foo; lines at the top of your file.

在大多数情况下，这是没有必要的，因为PHP会退回到不存在名称空间本地版本的全局/内置版本，但是在少数情况下，如果PHP事先知道所使用的版本，则会有性能优势（请参阅问题3048和PHP-CS-Fixer中的问题2739）。

在PHP-CS-Fixer中控制此选项为native_function_invocation。