Defining multiple namespaces in the same file
(PHP 5 >= 5.3.0, PHP 7, PHP 8)
Multiple namespaces may also be declared in the same file. There are two allowed syntaxes.
Example #1 Declaring multiple namespaces, simple combination syntax
<?php
namespace MyProject;
const CONNECT_OK = 1;
class Connection { /* ... */ }
function connect() { /* ... */ }
namespace AnotherProject;
const CONNECT_OK = 1;
class Connection { /* ... */ }
function connect() { /* ... */ }
?> This syntax is not recommended for combining namespaces into a single file. Instead it is recommended to use the alternate bracketed syntax.
Example #2 Declaring multiple namespaces, bracketed syntax
<?php
namespace MyProject {
const CONNECT_OK = 1;
class Connection { /* ... */ }
function connect() { /* ... */ }
}
namespace AnotherProject {
const CONNECT_OK = 1;
class Connection { /* ... */ }
function connect() { /* ... */ }
}
?> It is strongly discouraged as a coding practice to combine multiple namespaces into the same file. The primary use case is to combine multiple PHP scripts into the same file.
To combine global non-namespaced code with namespaced code, only bracketed syntax is supported. Global code should be encased in a namespace statement with no namespace name as in:
Example #3 Declaring multiple namespaces and unnamespaced code
<?php
namespace MyProject {
const CONNECT_OK = 1;
class Connection { /* ... */ }
function connect() { /* ... */ }
}
namespace { // global code
session_start();
$a = MyProject\connect();
echo MyProject\Connection::start();
}
?> No PHP code may exist outside of the namespace brackets except for an opening declare statement.
Example #4 Declaring multiple namespaces and unnamespaced code
<?php
declare(encoding='UTF-8');
namespace MyProject {
const CONNECT_OK = 1;
class Connection { /* ... */ }
function connect() { /* ... */ }
}
namespace { // global code
session_start();
$a = MyProject\connect();
echo MyProject\Connection::start();
}
?>
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https://www.php.net/manual/en/language.namespaces.definitionmultiple.php