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Namespaces and dynamic language features

(PHP 5 >= 5.3.0)

PHP's implementation of namespaces is influenced by its dynamic nature as a programming language. Thus, to convert code like the following example into namespaced code:

Example #1 Dynamically accessing elements

example1.php:

<?php
class classname
{
    function 
__construct()
    {
        echo 
__METHOD__,"\n";
    }
}
function 
funcname()
{
    echo 
__FUNCTION__,"\n";
}
const 
constname "global";

$a 'classname';
$obj = new $a// prints classname::__construct
$b 'funcname';
$b(); // prints funcname
echo constant('constname'), "\n"// prints global
?>
One must use the fully qualified name (class name with namespace prefix). Note that because there is no difference between a qualified and a fully qualified Name inside a dynamic class name, function name, or constant name, the leading backslash is not necessary.

Example #2 Dynamically accessing namespaced elements

<?php
namespace namespacename;
class 
classname
{
    function 
__construct()
    {
        echo 
__METHOD__,"\n";
    }
}
function 
funcname()
{
    echo 
__FUNCTION__,"\n";
}
const 
constname "namespaced";

include 
'example1.php';

$a 'classname';
$obj = new $a// prints classname::__construct
$b 'funcname';
$b(); // prints funcname
echo constant('constname'), "\n"// prints global

/* note that if using double quotes, "\\namespacename\\classname" must be used */
$a '\namespacename\classname';
$obj = new $a// prints namespacename\classname::__construct
$a 'namespacename\classname';
$obj = new $a// also prints namespacename\classname::__construct
$b 'namespacename\funcname';
$b(); // prints namespacename\funcname
$b '\namespacename\funcname';
$b(); // also prints namespacename\funcname
echo constant('\namespacename\constname'), "\n"// prints namespaced
echo constant('namespacename\constname'), "\n"// also prints namespaced
?>

Be sure to read the note about escaping namespace names in strings.

PHP Manual