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.
Defining namespaces
(PHP 5 >= 5.3.0, PHP 7)
Although any valid PHP code can be contained within a namespace, only the following types of code are affected by namespaces: classes (including abstracts and traits), interfaces, functions and constants.
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.
Example #1 Declaring a single namespace
<?php
namespace MyProject;
const CONNECT_OK = 1;
class Connection { /* ... */ }
function connect() { /* ... */ }
?>
Example #2 Declaring a single namespace
<html>
<?php
namespace MyProject; // fatal error - namespace must be the first statement in the script
?>
In addition, unlike any other PHP construct, the same namespace may be defined in multiple files, allowing splitting up of a namespace's contents across the filesystem.
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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...
