Defining multiple namespaces in the same file

(PHP 5 >= 5.3.0, PHP 7)

Multiple namespaces may also be declared in the same file. There are two allowed syntaxes.

Exemplo #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.

Exemplo #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:

Exemplo #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.

Exemplo #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 9 notes

up
28
leaksin [ at ] gmail [ dot ] com
3 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
9
Rahul Sonar
1 year 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
6
jigar dot vy at gmail dot com
1 year 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
3
Ishan Fernando
1 year 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
dominic_mayers at yahoo dot com
2 days ago
If you have the habit to always use the closing PHP tag "?>" in your test files, remember that with the bracketed syntax code outside the brackets, including new lines outside the PHP tags,  is not allowed.  In particular, even though PHP sees a new line after the closing tag  as a part of the line and eats it, some editors, such as  Gedit, Gvim, Vim and Nano in Ubuntu,  will  add yet another new line after this new line and this will create an error.
up
0
martin_winkel at hotmail dot com
1 month ago
In addition to  kothnok at gmail dot com

When using namespaces with brackets, you should define the USE statements within the brackets. His example sets the global use for the file.

<?php

namespace Space1;
use
SomeNamespace\FunctionCollection as FC;
{
    
FC\hello_world();
}

namespace
Space2;
{
    
// This can be used here
    
FC\hello_world();
}
?>

While the preferred method with brackets is this:
<?php

namespace Space1
{
     use
SomeNamespace\FunctionCollection as FC;
    
FC\hello_world();
}

namespace
Space2;
{
    
// This will not work now
    
FC\hello_world();
}
?>
up
0
Luis Pessoa
1 year 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
-1
dominic_mayers at yahoo dot com
6 days ago
With the bracketed syntax, a simple white space after the closing "?>" of the file, even a new line that is some times  considered as the end of a line and thus a part of the line, will (at the least in some php installations) be considered as code outside the brackets and will result in an error. It's general good practice to avoid white space after the closing "?>". Just pointing out that it is another case where it matters.
up
-1
maycon dot rodrigues1 at gmail dot com
6 months ago
Notice it's not allowed to mix bracketed namespace with unbracketed namespace declarations.

<?php
namespace MyTest;

const
TEST = 777;

//in this way
echo \MyTest\TEST . '<br />';

//Or this way
echo TEST . '<br />';

namespace
AnotherTest {

const
TEST = 555;

echo \
AnotherTest\TEST . '<br />';
echo \
MyTest\TEST;
}
?>

This code will issue a fatal error, like this: Fatal error: Cannot mix bracketed namespace declarations with unbracketed namespace declarations in C:\xampp\htdocs\teste2.php on line 11.
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