全局空间
(PHP 5 >= 5.3.0, PHP 7, PHP 8)
如果没有定义任何命名空间，所有的类与函数的定义都是在全局空间，与
PHP 引入命名空间概念前一样。在名称前加上前缀 \
表示该名称是全局空间中的名称，即使该名称位于其它的命名空间中时也是如此。
示例 #1 使用全局空间说明
<?php
namespace A\B\C;
/* 这个函数是 A\B\C\fopen */
function fopen() {
/* ... */
$f = \fopen(...); // 调用全局的fopen函数
return $f;
}
?>
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User Contributed Notes 4 notes
routinet ¶
10 years ago
Included files will default to the global namespace.
<?php
//test.php
namespace test {
include 'test1.inc';
echo '-',__NAMESPACE__,'-<br />';
}
?>
<?php
//test1.inc
echo '-',__NAMESPACE__,'-<br />';
?>
Results of test.php:
--
-test-
nobody at example dot com ¶
7 years ago
In namespaced context the Exception class needs to be prefixed with global prefix operator.
<?php
namespace hey\ho\lets\go;
class MyClass
{
public function failToCatch()
{
try {
$thing = somethingThrowingAnException();
} catch (Exception $ex) {
// Not catched
}
}
public function succeedToCatch()
{
try {
$thing = somethingThrowingAnException();
} catch (\Exception $ex) {
// This is now catched
}
}
}
hileon at gmail dot com ¶
6 years ago
This design of access globe name is bad, at least inconvenient.
In case that you have some legacy code, and try to copy and re-use it under some namespace. You have to add prefix "\" on any global function call.
xmarcos at gmail dot com ¶
10 years ago
That's the expected behavior, you have to declare the namespace at the top of the file to "extend" it.
If you include a global namespaced file, it will operate on the global namespace.
备份地址：http://www.lvesu.com/blog/php/language.namespaces.global.php