PHP 5.6.0 released

Définition des espaces de noms

(PHP 5 >= 5.3.0)

Bien que du code PHP valide puisse être contenu dans un espace de noms, seuls les types de code suivants peuvent être affectés par les espaces de noms : les classes (incluants les abstraites et les traits), les interfaces, les fonctions et les constantes.

Les espaces de noms sont déclarés avec le mot-clé namespace. Un fichier contenant un espace de noms doit déclarer l'espace au début du fichier, avant tout autre code, avec une seule exception : le mot clé declare.

Exemple #1 Déclaration d'un espace de noms

<?php
namespace MonProjet;

const 
CONNEXION_OK 1;
class 
Connexion /* ... */ }
function 
connecte() { /* ... */  }

?>
Le seul élément autorisé avant la déclaration d'espace de noms est la commande declare, pour définir l'encodage du fichier source. De plus, aucun code non-PHP ne peut précéder la déclaration d'espace de noms, y compris des espaces :

Exemple #2 Erreur de déclaration d'un espace de noms

<html>
<?php
namespace MonProjet// erreur fatale : l'espace de noms doit être le premier élément du script
?>

De plus, contrairement à d'autres structures PHP, le même espace de noms peut être défini dans plusieurs fichiers, ce qui permet de scinder le contenu d'un espace de noms sur plusieurs fichiers.

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User Contributed Notes 10 notes

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39
danbettles at yahoo dot co dot uk
5 years ago
Regarding constants defined with define() inside namespaces...

define() will define constants exactly as specified.  So, if you want to define a constant in a namespace, you will need to specify the namespace in your call to define(), even if you're calling define() from within a namespace.  The following examples will make it clear.

The following code will define the constant "MESSAGE" in the global namespace (i.e. "\MESSAGE").

<?php
namespace test;
define('MESSAGE', 'Hello world!');
?>

The following code will define two constants in the "test" namespace.

<?php
namespace test;
define('test\HELLO', 'Hello world!');
define(__NAMESPACE__ . '\GOODBYE', 'Goodbye cruel world!');
?>
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20
jeremeamia at gmail dot com
5 years ago
You should not try to create namespaces that use PHP keywords. These will cause parse errors.

Examples:

<?php
namespace Project/Classes/Function; // Causes parse errors
namespace Project/Abstract/Factory; // Causes parse errors
?>
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14
FatBat
1 year ago
Expanding on @danbettles note, it is better to always be explicit about which constant to use.

<?php
   
namespace NS;

   
define(__NAMESPACE__ .'\foo','111');
   
define('foo','222');

    echo
foo// 111.
   
echo \foo// 222.
   
echo \NS\foo  // 111.
   
echo NS\foo  // fatal error. assumes \NS\NS\foo.
?>
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17
huskyr at gmail dot com
4 years ago
"A file containing a namespace must declare the namespace at the top of the file before any other code"

It might be obvious, but this means that you *can* include comments and white spaces before the namespace keyword.

<?php
// Lots
// of
// interesting
// comments and white space

namespace Foo;
class
Bar {
}
?>
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5
Baptiste
6 years ago
There is nothing wrong with PHP namespaces, except that those 2 instructions give a false impression of package management.
... while they just correspond to the "with()" instruction of Javascript.

By contrast, a package is a namespace for its members, but it offers more (like deployment facilities), and a compiler knows exactly what classes are in a package, and where to find them.
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2
Anonymous
6 years ago
@ RS: Also, you can specify how your __autoload() function looks for the files. That way another users namespace classes cannot overwrite yours unless they replace your file specifically.
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2
David Drakard
5 years ago
I agree with SR, the new namespaces feature has solved a number of problems for me which would have required horrible coding to solve otherwise.

An example use:
Say you are making a small script, and write a class to connect to a database, calling it 'connection'. If you find your script useful and gradually expand it into a large application, you may want to rename the class. Without namespaces, you have to change the name and every reference to it (say in inheriting objects), possibly creating a load of bugs. With namespaces you can drop the related classes into a namespace with one line of code, and less chance of errors.

This is by no means one of the biggest problems namespaces solve; I would suggest reading about their advantages before citicising them. They provide an elegant solutions to several problems involved in creating complex systems.
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0
kuzawinski dot marcin at NOSPAM dot gmail dot com
25 days ago
If your code looks like this:

<?php
   
namespace NS;
?>

...and you still get "Namespace declaration statement has to be the very first statement in the script" Fatal error, then you probably use UTF-8 encoding (which is good) with Byte Order Mark, aka BOM (which is bad). Try to convert your files to "UTF-8 without BOM", and it should be ok.
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-4
Roadowl
6 months ago
quote:
Defining namespaces

(...)
Namespaces are declared using the namespace keyword. A file containing a namespace must declare the namespace at the top of the file before any other code - with one exception: the declare keyword.

end quote.

So we have a title that talks 'defining' and a piece of text that talks 'declare' three times, one of which could be referring to some other 'declare' than the former two.

Please, documentation authors -- get your act together, finally.
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-24
wyattbiker
1 year ago
<?php
//Even though you cant add anything before the 1st namespace, you can add something before subsequent namespaces.
namespace MyProject;

function
myfunc(){
    return
1;
}
echo
myfunc();
?>
<p>Here I can add stuff before the 2nd namespace</p>
<?php

namespace MyProject2;

function
myfunc(){
    return
2;
}
echo
myfunc();
?>
<p>Switch back to first namespace</p>
<?php
namespace MyProject;
echo
myfunc();
?>
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