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.
Definir espacios de nombres
(PHP 5 >= 5.3.0, PHP 7, PHP 8)
Aunque cualquier código de PHP válido puede estar contenido dentro de un espacio de nombres, solamente se ven afectados por espacios de nombres los siguientes tipos de código: clases (incluyendo abstractas y traits), interfaces, funciones y constantes.
Los espacios de nombres se declaran utilizando la palabra reservada namespace.
Un fichero que contenga un espacio de nombres debe declararlo al inicio
del mismo, antes que cualquier otro código, con una excepción: la
palabra reservada declare.
Ejemplo #1 Declarar un único espacio de nombres
<?php
namespace MiProyecto;
const CONECTAR_OK = 1;
class Conexión { /* ... */ }
function conectar() { /* ... */ }
?>declare para declarar la codificación de un fichero fuente. Además,
todo lo que no sea código de PHP no puede preceder a la declaración del espacio de nombres, incluyendo espacios en blanco extra:
Ejemplo #2 Declarar un único espacio de nombres
<html>
<?php
namespace MiProyecto; // error fatal - el espacio de nombres debe ser la primera sentencia del script
?>También, a diferencia de otras construcciones de PHP, se puede definir el mismo espacio de nombres en varios ficheros, permitiendo la separación del contenido de un espacio de nombres a través del sistema de ficheros.
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User Contributed Notes 10 notes
kuzawinski dot marcin at NOSPAM dot gmail dot com ¶
10 years ago
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!');
?>
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.
?>
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
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 {
}
?>
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
?>
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.
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.
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.
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...
