PHP 5.4.33 Released

Namespaces definieren

(PHP 5 >= 5.3.0)

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-Schlüsselworts.

Beispiel #1 Einen einzelnen Namespace deklarieren

<?php
namespace MyProject;

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

?>
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 11 notes

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44
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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22
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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17
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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18
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
6 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
Najeem M Illyas
16 hours ago
While executing the script I am getting error:

<?php
namespace SebastianBergmann\Money;
/**
* Money
*
/

class MoneyTest extends \PHPUnit_Framework_TestCase
{
    /**
  
}

?>

C:\>phpunit --coverage-html ./report C:\xampp\htdocs\unit

Fatal error: Namespace declaration statement has to be the very first statement
in the script in C:\xampp\htdocs\unit\MoneyTest.php on line 2

Call Stack:
    0.0000     124064   1. {main}() C:\xampp\php\phpunit:0
    0.0000     359648   2. PHPUnit_TextUI_Command::main() C:\xampp\php\phpunit:4
6
    0.0000     363064   3. PHPUnit_TextUI_Command->run() C:\xampp\php\pear\PHPUn
it\TextUI\Command.php:129
    0.0100     542472   4. PHPUnit_Runner_BaseTestRunner->getTest() C:\xampp\php
\pear\PHPUnit\TextUI\Command.php:150
    0.0100     681336   5. PHPUnit_Framework_TestSuite->addTestFiles() C:\xampp\
php\pear\PHPUnit\Runner\BaseTestRunner.php:96
    0.0100     681768   6. PHPUnit_Framework_TestSuite->addTestFile() C:\xampp\p
hp\pear\PHPUnit\Framework\TestSuite.php:416
    0.0200     739488   7. PHPUnit_Util_Fileloader::checkAndLoad() C:\xampp\php\
pear\PHPUnit\Framework\TestSuite.php:355
    0.0200     739600   8. PHPUnit_Util_Fileloader::load() C:\xampp\php\pear\PHP
Unit\Util\Fileloader.php:76

Here in the error:
Fatal error: Namespace declaration statement has to be the very first statement
in the script in C:\xampp\htdocs\unit\MoneyTest.php on line 2

There is no error found in the code, but phpunit is throwing the error.
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0
kuzawinski dot marcin at NOSPAM dot gmail dot com
1 month 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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-2
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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