PHP: Définition des espaces de noms

Last updated: Fri, 14 Aug 2009

Définition des espaces de noms

Bien que du code PHP valide puisse être contenu dans un espace de noms, seuls trois types de code peuvent être affectés par les espaces de noms : les classes, 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.

Déclaration d'un sous espace de noms

Introduction aux espaces de noms

Last updated: Fri, 14 Aug 2009

add a note User Contributed Notes
Définition des espaces de noms

huskyr at gmail dot com
05-Oct-2009 11:20


"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 {


}


?>

jurrien at jpdokter dot nl
04-Aug-2009 08:21


I have written a Packager class that allows to use packages and namespaces. It does require the folder layout. If the __autoload function is not yet "re-implemented", it'll create its own __autoload function.



It is written in PHP5 and does not require > PHP5.3, moreover, I don't have PHP5.3 since XAMPP is not adding it yet. Don't ask me why.



Since it's over 300 lines long, I am not going to post it here. But if someone would like to have a look?



Basic uses:



<?php



# /classes

#     /package1

#         class34.class.php

#     /package2

#         classone.class.php



require_once('packager.class.php');



#Packager::debug(true);



Packager::addClasspath(dirname(__FILE__).'/classes', true); // true means that it overrules the predefined set.

Packager::addClassSuffix(array('.class.php'),true); // true means that it overrules the predefined set.



Packager::import("package1.Class34"); // java-style

Packager::import("package2::ClassOne"); // php-style



echo Packager::dump(); // show us what you got!



?>

jeremeamia at gmail dot com
14-Jul-2009 03:43


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


?>

danbettles at yahoo dot co dot uk
14-Apr-2009 07:02


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!');

?>

David Drakard
07-Sep-2008 12:56


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.

Baptiste
14-May-2008 07:47


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.

Anonymous
01-Apr-2008 07:11


@ 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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Déclaration d'un sous espace de noms

Introduction aux espaces de noms

Last updated: Fri, 14 Aug 2009