PHP 8.4.2 Released!

    Namespaces definieren

    (PHP 5 >= 5.3.0, PHP 7, PHP 8)

    Obwohl jeder gültige PHP-Quellcode in Namespaces eingeschlossen werden kann, werden nur die folgenden Arten von Code von Namespaces beeinflusst: Klassen (inklusive abstrakter Klassen und Traits), Interfaces, 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-Schlüsselwortes.

    Beispiel #1 Einen einzelnen Namespace deklarieren

    <?php
    namespace MyProject;

    const     CONNECT_OK = 1;
    class     Connection { /* ... */ }
    function     connect() { /* ... */ }

    ?>

    Hinweis: Vollständig qualifizierte Namen (d. h. Namen, die mit einem Rückwärtsschrägstrich beginnen) sind in Namensraumdeklarationen nicht erlaubt, weil solche Konstrukte als relative Namensraumausdrücke interpretiert werden.

    Der einzige Quellcode, der vor einer Namespacedeklaration stehen darf, ist der declare-Ausdruck, der die Kodierung der Quellcodedatei definiert. Gleichzeitig darf kein Nicht-PHP-Code vor einer Namespacedeklaration stehen - auch keine zusätzlichen Leerzeichen, Zeilenumbrüche oder Tabulatoren.

    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.

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    User Contributed Notes 10 notes

    up
    205
    kuzawinski dot marcin at NOSPAM dot gmail dot com
    10 years 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.
    up
    142
    danbettles at yahoo dot co dot uk
    15 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!');
    ?>
    up
    9
    anisgazig at gmail dot com
    3 years ago
    namespace statement is defined at first of the php files. But
    before namespace declaration only three elements allowed.
    1.declare statement
    2.spaces
    3.comments
    up
    84
    FatBat
    11 years 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.
    ?>
    up
    65
    huskyr at gmail dot com
    15 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 {
    }
    ?>
    up
    48
    jeremeamia at gmail dot com
    15 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
    ?>
    up
    1
    dino at tuxweb dot it
    2 years ago
    Please note that a PHP Namespace declaration cannot start with a number.
    It took some time for me to debug...
    up
    6
    Anonymous
    16 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.
    up
    1
    Baptiste
    16 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.
    up
    -2
    anisgazig at gmail dot com
    3 years ago
    Namespace name are case-insensitive.
    namespace App
    and
    namespace app
    are same meaning.

    Besides, Namespace keword are case-insensitive.
    Namespace App
    namespace App
    and
    NAMESPACE App
    are same meaning.
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