Just in case you wonder what the practical use of the namespace keyword is...
It can explicitly refer to classes from the current namespace regardless of possibly "use"d classes with the same name from other namespaces. However, this does not apply for functions.
Example:
<?php
namespace foo;
class Xyz {}
function abc () {}
?>
<?php
namespace bar;
class Xyz {}
function abc () {}
?>
<?php
namespace bar;
use foo\Xyz;
use foo\abc;
new Xyz(); // instantiates \foo\Xyz
new namespace\Xyz(); // instantiates \bar\Xyz
abc(); // invokes \bar\abc regardless of the second use statement
\foo\abc(); // it has to be invoked using the fully qualified name
?>
Hope, this can save someone from some trouble.
Best regards.
namespace keyword and __NAMESPACE__ constant
(PHP 5 >= 5.3.0, PHP 7)
PHP supports two ways of abstractly accessing elements within the current namespace,
the __NAMESPACE__ magic constant, and the namespace
keyword.
The value of __NAMESPACE__ is a string that contains the current
namespace name. In global, un-namespaced code, it contains an empty string.
Example #1 __NAMESPACE__ example, namespaced code
<?php
namespace MyProject;
echo '"', __NAMESPACE__, '"'; // outputs "MyProject"
?>
Example #2 __NAMESPACE__ example, global code
<?php
echo '"', __NAMESPACE__, '"'; // outputs ""
?>
__NAMESPACE__ constant is useful for dynamically constructing
names, for instance:
Example #3 using __NAMESPACE__ for dynamic name construction
<?php
namespace MyProject;
function get($classname)
{
$a = __NAMESPACE__ . '\\' . $classname;
return new $a;
}
?>
The namespace keyword can be used to explicitly request an element from the current namespace or a sub-namespace. It is the namespace equivalent of the self operator for classes.
Example #4 the namespace operator, inside a namespace
<?php
namespace MyProject;
use blah\blah as mine; // see "Using namespaces: Aliasing/Importing"
blah\mine(); // calls function MyProject\blah\mine()
namespace\blah\mine(); // calls function MyProject\blah\mine()
namespace\func(); // calls function MyProject\func()
namespace\sub\func(); // calls function MyProject\sub\func()
namespace\cname::method(); // calls static method "method" of class MyProject\cname
$a = new namespace\sub\cname(); // instantiates object of class MyProject\sub\cname
$b = namespace\CONSTANT; // assigns value of constant MyProject\CONSTANT to $b
?>
Example #5 the namespace operator, in global code
<?php
namespace\func(); // calls function func()
namespace\sub\func(); // calls function sub\func()
namespace\cname::method(); // calls static method "method" of class cname
$a = new namespace\sub\cname(); // instantiates object of class sub\cname
$b = namespace\CONSTANT; // assigns value of constant CONSTANT to $b
?>
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User Contributed Notes 3 notes
a dot schaffhirt at sedna-soft dot de ¶
14 years ago
bharatthapa45 at gmail dot com ¶
2 years ago
Difference between __NAMESPACE__ and keyword 'namespace' that I find relevant is when invoking a class:
<?php
namespace MyApp;
class App {
static function app(){
echo 'hello app';
}
}
// this will work:
$obj = new namespace\App::app();
// this will not work
$obj = new __NAMESPACE__\App::app();
// however this will work:
$obj = __NAMESPACE__ . '\App';
$obj::foo();
?>
cornichonche at gmail dot com ¶
6 years ago
The example 4 is wrong.
Using php 7.2
<?php
namespace monProjet;
use function blah\blah as mine;
blah\mine(); // Will NOT work
mine(); // Will work
?>
