全局空间
(PHP 5 >= 5.3.0)
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。
Example #1 使用全局空间说明
<?php
namespace A \ B \ C ;
function fopen () {
$f = \ fopen (...); // 调用全局的fopen函数
return $f ;
}
?> 用户评论:
[#1] hileon at gmail dot com [2015-11-25 08:17:15]
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.
[#2] nobody at example dot com [2015-05-15 07:59:58]
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
}
}
}
[#3] xmarcos at gmail dot com [2012-05-21 19:08:50]
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.
[#4] routinet [2011-08-28 23:22:14]
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-