(PHP 5 >= 5.3.0, PHP 7, PHP 8)
Without any namespace definition, all class and function definitions are
placed into the global space - as it was in PHP before namespaces were
supported. Prefixing a name with \ will specify that
the name is required from the global space even in the context of the
namespace.
Example #1 Using global space specification
<?php
namespace A\B\C;
/* This function is A\B\C\fopen */
function fopen() {
/* ... */
$f = \fopen(...); // call global fopen
return $f;
}
?>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-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;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
}
}
}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.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.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.