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Defining multiple namespaces in the same file

(PHP 5 >= 5.3.0)

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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