IT. Expert System.

PHP

Namespaces overview


Namespaces overview

(PHP 5 >= 5.3.0)

What are namespaces? In the broadest definition namespaces are a way of encapsulating items. This can be seen as an abstract concept in many places. For example, in any operating system directories serve to group related files, and act as a namespace for the files within them. As a concrete example, the file foo.txt can exist in both directory /home/greg and in /home/other, but two copies of foo.txt cannot co-exist in the same directory. In addition, to access the foo.txt file outside of the /home/greg directory, we must prepend the directory name to the file name using the directory separator to get /home/greg/foo.txt. This same principle extends to namespaces in the programming world.

In the PHP world, namespaces are designed to solve two problems that authors of libraries and applications encounter when creating re-usable code elements such as classes or functions:

  1. Name collisions between code you create, and internal PHP classes/functions/constants or third-party classes/functions/constants.
  2. Ability to alias (or shorten) Extra_Long_Names designed to alleviate the first problem, improving readability of source code.

PHP Namespaces provide a way in which to group related classes, interfaces, functions and constants. Here is an example of namespace syntax in PHP:

Example #1 Namespace syntax example

<?php
namespace my\name// see "Defining Namespaces" section

class MyClass {}
function 
myfunction() {}
const 
MYCONST 1;

$a = new MyClass;
$c = new \my\name\MyClass// see "Global Space" section

$a strlen('hi'); // see "Using namespaces: fallback to global
                   // function/constant" section

$d = namespace\MYCONST// see "namespace operator and __NAMESPACE__
                        // constant" section
$d __NAMESPACE__ '\MYCONST';
echo 
constant($d); // see "Namespaces and dynamic language features" section
?>

Note:

Namespace names PHP and php, and compound names starting with these names (like PHP\Classes) are reserved for internal language use and should not be used in the userspace code.



Content

Android Reference

Java basics

Java Enterprise Edition (EE)

Java Standard Edition (SE)

SQL

HTML

PHP

CSS

Java Script

MYSQL

JQUERY

VBS

REGEX

C

C++

C#

Design patterns

RFC (standard status)

RFC (proposed standard status)

RFC (draft standard status)

RFC (informational status)

RFC (experimental status)

RFC (best current practice status)

RFC (historic status)

RFC (unknown status)

IT dictionary

License.
All information of this service is derived from the free sources and is provided solely in the form of quotations. This service provides information and interfaces solely for the familiarization (not ownership) and under the "as is" condition.
Copyright 2016 © ELTASK.COM. All rights reserved.
Site is optimized for mobile devices.
Downloads: 254 / 158767626. Delta: 0.03246 с