(PHP 5 >= 5.3.0, PHP 7, PHP 8)
名前空間の定義がない場合、すべてのクラスや関数の定義はグローバル空間に配置されます。 これは、名前空間に対応する前の PHP がサポートしていた空間です。 名前の先頭に\ をつけると、 名前空間の内部からであってもグローバル空間の名前を指定することができます。
例1 グローバル空間を指定する方法
<?php
namespaceA\B\C;
/* この関数は A\B\C\fopen です */
functionfopen() {
/* ... */
$f=\fopen(...);// グローバルな fopen をコールします
return$f;
}
?>Included files will default to the global namespace.<?php//test.phpnamespacetest{ include'test1.inc'; echo'-',__NAMESPACE__,'-<br />';}?><?php//test1.incecho'-',__NAMESPACE__,'-<br />';?>Results of test.php:---test-In namespaced context the Exception class needs to be prefixed with global prefix operator.<?phpnamespacehey\ho\lets\go;classMyClass{ public functionfailToCatch() { try {$thing=somethingThrowingAnException(); } catch (Exception $ex) {// Not catched} } public functionsucceedToCatch() { try {$thing=somethingThrowingAnException(); } catch (\Exception $ex) {// This is now catched} }}To define an associative array (hash) so that it is part of the namespace, instead of going into the global namespace, just declare it as const, istead of as a variable.This is handy for lookup tables, config settings, etc.// Example. Instead of writing:$my_datatypes = [ "sterility" => [ "xlsx" => [ "Sample Type", "Run Pass/Fail", "Result" ], "db" => [ "SampleType", "RunPassFail", "Result" ] ]];// ...declare the lookup table like this:const MY_DATATYPES = [ "sterility" => [ "xlsx" => [ "Sample Type", "Run Pass/Fail", "Result" ], "db" => [ "SampleType", "RunPassFail", "Result" ] ]];// ...and it will be declared within the current namespace.Note that variables aren't part of the namespace so they are always global (or scoped to function, etc.) and can't be accessed the same way as other namespace stuff.So no: namespace Foo; $var = "hello"; echo \Foo\$var;