wyattbiker (2013-06-01 00:19:45)

<?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();
?>

parsmizban.com (2012-06-12 11:02:39)

You can use this as a namespace declaration:

<?php
declare(encoding='UTF-8');
namespace parsmizban;

echo "parsmizban";
?>

huskyr at gmail dot com (2009-10-05 04:20:48)

"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 (2009-07-14 08:43:55)

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
?>

danbettles at yahoo dot co dot uk (2009-04-14 12:02:21)

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!');
?>

David Drakard (2008-09-07 05:56:02)

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.

Baptiste (2008-05-14 12:47:03)

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.

Anonymous (2008-04-01 11:11:34)

@ 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.