How to use namespaces in PHP classes?

Question

also how to get class from php plugins in my namespace?

Answer 1

Syntax for extending classes in namespaces is still the same. 

Lets call this Object.php: 

<?php 

namespace com\rsumilang\common; 

class Object{ 
   // ... code ... 
} 

?> 

And now lets create a class called String that extends object in String.php: 

<?php 

class String extends com\rsumilang\common\Object{ 
   // ... code ... 
} 

?> 

Now if you class String was defined in the same namespace as Object then you don't have to specify a full namespace path: 

<?php 

namespace com\rsumilang\common; 

class String extends Object 
{ 
   // ... code ... 
} 

?> 

Lastly, you can also alias a namespace name to use a shorter name for the class you are extending incase your class is in seperate namespace: 

<?php 

namespace com\rsumilang\util; 
use com\rsumlang\common as Common; 

class String extends Common\Object 
{ 
   // ... code ... 
} 

?> 

source: http://php.net/manual/en/language.namespaces.basics.php

Answer 2

To declare a namespace, use the namespace command followed by the name of the namespace to create. Nothing should be placed before, whether it's HTML or just a line break. No instructions must be written before the namespace declaration (except the declare statement).
SIMPLE EXAMPLE:
--------------------------------
<?php

namespace MonNamespace;
function strlen()
{
echo 'Hello world !';
}

?>