Diese Seite bei php.net
The PHP manual text and comments are covered by the Creative Commons Attribution 3.0 License © the PHP Documentation Group - Impressum - mail("TO:Reinhard Neidl",...)
Obwohl jeder gültige PHP-Quellcode in Namespaces eingeschlossen werden kann, werden nur drei Arten von Code von Namespaces beeinflusst: Klassen, Funktionen und Konstanten.
Namespaces werden mit dem Schlüsselwort namespace definiert. Eine Datei, die einen Namespace beinhaltet, muss den Namespace am Anfang der Datei vor jeglichem anderen Code deklarieren - mit Ausnahme des declare-Schlüsselworts.
Beispiel #1 Einen einzelnen Namespace deklarieren
<?php
namespace MyProject;
const CONNECT_OK = 1;
class Connection { /* ... */ }
function connect() { /* ... */ }
?>
Beispiel #2 Einen einzelnen Namespace deklarieren
<html>
<?php
namespace MyProject; // fatal error - Namespace muss der erste Ausdruck im Skript sein
?>
Zusätzlich darf - im Gegensatz zu anderen PHP-Konstrukten - der selbe Namespace in mehreren Dateien definiert werden, womit man den Inhalt eines Namespaces im Dateisystem aufteilen kann.
"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 {
}
?>
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!
?>
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
?>
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!');
?>
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.
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.
@ 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.
Diese Seite bei php.net