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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User Contributed Notes 7 notes

up
6
Rahul Sonar
6 months ago
<?php
//Namespace can be used in this way also
namespace MyProject {

function
connect() { echo "ONE";  }
   
Sub\Level\connect();
}

namespace
MyProject\Sub {
   
function
connect() { echo "TWO";  }
   
Level\connect();
}

namespace
MyProject\Sub\Level {
   
    function
connect() { echo "THREE";  }   
    \
MyProject\Sub\Level\connect(); // OR we can use this as below
   
connect();
}
up
52
kothnok at gmail dot com
3 years ago
"use" statements are required to be placed after the "namespace my\space" but before the "{".
e.g.

<?php
namespace foo\bar;
use
my\space\MyClass;
{

// place code here

} // end of namespace foo\bar

namespace another\bar;
use
my\space\MyClass;
use
my\space\AnotherClass;
{

// place code here

} // end of namespace another\bar
?>
up
24
leaksin [ at ] gmail [ dot ] com
2 years ago
using of global namespaces and multiple namespaces in one PHP file increase the complexity and decrease readability of the code.
Let's try not use this scheme even it's very necessary (although there is not)
up
2
jigar dot vy at gmail dot com
2 months ago
<?php

// You cannot mix bracketed namespace declarations with unbracketed namespace declarations - will result in a Fatal error

namespace a;

echo
"I belong to namespace a";

namespace
b {
    echo
"I'm from namespace b";
}
up
1
Ishan Fernando
2 months ago
//call same named function using namespace

//food.php

<?php
namespace Food;

require (
'Apple.php');
require(
'Orange.php');

use
Apples;
use
Oranges;

 
Apples\eat();
 
Oranges\eat();
?>

//Apple.php
<?php
namespace Apples;

function
eat()
{
  echo
"eat apple";
}
?>

//Orange.php
<?php
namespace Oranges;

function
eat()
{
  echo
"eat Orange";
}
?>
up
0
Luis Pessoa
4 months ago
Be careful with include combined to namespaces:

file b.php
<?php
   
const WHERE_I_AM = 'I am in B';
   
    function
i_am_in() {
        \
A\cr_echo(WHERE_I_AM);
    }
?>

file c.php
<?php
   
namespace C {
        const
WHERE_I_AM = 'I am in C';
       
        function
i_am_in() {
            \
A\cr_echo(WHERE_I_AM);
        }
    }
?>

main file

<?php
  
   
namespace A {
   
        const
CR = "\r\n";
        const
WHERE_I_AM = 'I am in A';
       
        function
cr_echo($msg) {
            echo
$msg . CR;
        }
       
        function
i_am_in() {
           
cr_echo(WHERE_I_AM);
        }
    }
   
    namespace
B {
        require
'b.php';
    }
   
    namespace {
        require
'c.php';
       
        \
A\i_am_in(); //ok
       
\B\i_am_in(); // fatal-error
       
\C\i_am_in(); //ok
   
}
?>
up
-96
1932 at bk dot ru
1 year ago
last two examples give:

Fatal error: Call to undefined method MyProject\Connection::start() in Z:\home\test1.ru\www\link.php on line 12
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