Mastering PHP Namespaces PFCongres11

MASTERING NAMESPACES! Nick Belhomme Spetember 17, 2011 – PFCongres The Netherlands

Software Architect / Project Lead Author of the Zend Framework 2.0 Cookbook International Conference Speaker Contributor to various Open Source Projects Freelance PHP Consultant

www.nickbelhomme.com @NickBelhomme facebook.com/NickBelhommeFanPage Freenode irc: NickBelhomme

Other big programming languages support them Introduced in PHP 5.3 – Two years ago Modern Next Gen Frameworks (Symfony 2.0, Zend Framework 2.0 and others) Job market demands it Use it or loose it

WHAT ARE THEY ?

Abstract container created to hold a logical grouping of unique identifiers. Unique identifiers are names. (in practice: classes, functions, constants) Each identifier is associated with the namespace where it is defined. Namespace ZendControllerAction Namespace ZendView Namespace Nbe HelperLoader HelperBroker HelperPriorityStack E_ERROR explode HelperLoader HelperBroker PhpRenderer Namespace ArrayObject explode E_ERROR ArrayObject

Namespace Separator

PEAR Naming Convention R.I.P. No more clever workaround for lack of namespace support No more very long function and class names R.I.P. Poor man's namespacing

new Zend_Layout_Controller_Action_Helper_Layout() class NbeZf_Model_User extends Nbe_Model_Abstract

new Zend_Layout_Controller_Action_Helper_Layout() new Layout() class NbeZf_Model_User extends Nbe_Model_Abstract class User extends AbstractModel

100% PURE NAMESPACES No supplements – Pure Power

The container space is created per file at the absolute top <?php namespace NbeCollection; <?php declare(encoding='UTF-8'); namespace NbeCollection; <?php /** * @namespace */ namespace NbeCollection;

Mixing Container Spaces per file <?php namespace NbeModel; const LIBRARY_PATH = '/www/libs/Nbe'; class AbstractModel { /* ... */ } function draw() { /* ... */ } namespace NbeZf; const LIBRARY_PATH = '/www/libs/NbeZf'; class AbstractModel { /* ... */ } function sayHello() { /* ... */ } <?php namespace NbeModel { const LIBRARY_PATH = '/www/libs/Nbe'; class AbstractModel { /* ... */ } function draw() { /* ... */ } } namespace { const APP_PATH = '/www/libs/NbeZf'; function __autoload() { /* ... */ } }

Common Mistakes <?php namespace Nbe ; // rest of code Fatal error: Undefined constant 'Nbe' <?php namespace Nbe; class Interface {} <?php namespace Nbe; class Abstract {} Parse error: syntax error, unexpected T_INTERFACE Parse error: syntax error, unexpected T_ABSTRACT

Different name types Fully Qualified Name NbeModelAbstractModel Qualified Name ModelAbstractModel Unqualified Name AbstractModel

Autoloading namespaces function __autoload($class) { require_once str_replace( '', DIRECTORY_SEPARATOR, $class ) . '.php'; } new NbeZfModelUser() maps to NbeZfModelUser require_once NbeZf/Model/User.php

Autoloading namespaces <?php namespace NbeLoader; function autoLoader($className) { require_once str_replace('', DIRECTORY_SEPARATOR, $className) . '.php'; } <?php require 'Nbe/Loader/autoloader.php'; spl_autoload_register('NbeLoaderautoloader'); $user = new NbeEntityUser();

Resolving namespace calls <?php namespace Nbe; class Model {} $model = new Model(); echo get_class($model); Output: Nbe Model <?php namespace Nbe; function model() { return __FUNCTION__; } echo model(); Output: Nbemodel

Resolving namespace calls <?php namespace Nbe; class Model {} $model = new Model(); echo get_class($model); Output: NbeModel <?php namespace Nbe; function model() { return __FUNCTION__; } echo model(); Output: Nbemodel

Consequences <?php namespace Nbe; $collection = new ArrayObject(); Fatal error: Class 'NbeArrayObject' not found <?php namespace Nbe; $collection = new ArrayObject(); Indicate global namespace with a single backslash <----

Function fallbacks happen at Runtime <?php namespace Nbe; var_dump(explode(';', ' some;cool;words '));

Warning system functions within namespaces – Procedural Code <?php namespace WackyCode; var_dump( explode(';', 'some;cool;words')); Don't override system functions Or explicitly call global space FULLY QUALIFIED NAMES Compile time <---- <?php namespace WackyCode; function explode($separator, $string) { // do some freaky stuff }

(Procedural) Constants fallbacks <?php namespace Nbe { echo E_ERROR; }

(Procedural) Constants fallbacks <?php namespace Nbe { E_ERROR = 10; } <?php namespace Nbe { echo E_ERROR; } <?php namespace Nbe { echo E_ERROR; } Do not override system constants or Explicitly call global space Fully quaylified names, compile time

Fully Qualified Name Compile Time Qualified || Unqualified Name Runtime

Classses have no fallback to global scope Functions when not found in namespace fall back on global scope Constants when not found in namespace fall back on global scope

Magic constants beware <?php namespace Nbe; echo __LINE__; echo __FILE__; echo __DIR__; echo __FUNCTION__; echo __CLASS__; echo __METHOD__; echo __NAMESPACE__; Magic constants cannot be overwritten so no global namespace prefix is allowed

Namespaces are per file // utils.php <?php function sayHello() { echo 'hello'; } <?php namespace Nbe; require '/utils.php'; sayHello();

Mixing Namespaces Fully Qualified namespace calling is still tedious. So how do we solve this?

Importing to the rescue! Keyword is use

Importing to the rescue! <?php namespace DancingQueenEntity ; use NbeZfEntityAbstractEntity ; use ZendValidatorStaticValidator ; class User extends AbstractEntity { public function setId($id) { If (! StaticValidator ::execute($id, 'digits')) { throw new InvalidArgumentException ('User id needs to be numeric'); } ... } }

Importing to the rescue! <?php namespace DancingQueenEntity ; use NbeZfEntityAbstractEntity , ZendValidatorStaticValidator ; class User extends AbstractEntity { public function setId($id) { If (! StaticValidator ::execute($id, 'digits')) { throw new InvalidArgumentException ('User id needs to be numeric'); } ... } }

OOOH Noes a naming collision :((( <?php namespace NbeZfValidator; use ZendValidator StaticValidator ; class StaticValidator extends StaticValidator { public static function getBroker() { if (null === self::$broker) { static::setBroker(new ValidatorBroker()); } return self::$broker; } } Fatal error: Cannot declare class NbeZfValidatorStaticValidator because the name is already in use

Aliasing to the rescue! <?php namespace NbeZfValidator; use ZendValidatorStaticValidator as ZfStaticValidator; class StaticValidator extends ZfStaticValidator { public static function getBroker() { if (null === self::$broker) { static::setBroker(new ValidatorBroker()); } return self::$broker; } } Aliasing only supported for classes

Aliasing is in-explicitly used <?php namespace DancingQueenEntity; use NbeZfEntity AbstractEntity as AbstractEntity , ZendValidator StaticValidator as StaticValidator ; class User extends AbstractEntity { public function setId($id) { If (! StaticValidator ::execute($id, 'digits')) { throw new InvalidArgumentException('User id needs to be numeric'); } ... } } Aliasing is done at compile time

Aliasing for semantics <?php namespace Nbe; use NbeUserCollection as Users ; class Group { public function setUsers( Users $users) { $this->users = $users; } } Great for typehinting Focusing on the WHAT IS – instead on language type

Aliasing for semantics <?php namespace Nbe; use NbeUserCollection as Users ; class Group { public function setUsers($users) { if ($users instanceof Users ) { $this->users = $users; } } } Great for typehinting Focusing on the WHAT IS – instead on language type

Dynamic Loading

Always at runtime … <?php namespace Nbe; $class = 'ArrayObject'; $object = new $class(); echo get_class($object); Output: ArrayObject … Implies absolute path or Fully Qualified Names

Always use fully qualified names for dynamic class names if they are used! <?php namespace Nbe; class Group { public function setUsers($users) { $class = 'NbeUserCollection'; if ($users instanceof $class ) { $this->users = $users; } } } Even if you are in the current namespace

From other namespace <?php namespace Nbe; $class = 'ZendViewPhpRenderer'; $object = new $class(); echo get_class($object); Ouput: ZendViewPhpRenderer

Dynamic Loading from current <?php namespace Nbe; $class = __NAMESPACE__ . '' . 'ArrayObject' ; $object = new $class(); echo get_class($object); Output: NbeArrayObject User Magic Constant __NAMESPACE__

Resolution Rules <?php namespace Nbe; use TataNbe; $object = new ArrayObject(); <?php namespace Nbe; use TataNbe; $object = new NbeArrayObject(); Resolves to NbeArrayObject Resolves to TataNbeArrayObject

Resolution Rules for Dummies When an alias is available – and there is always an alias available when importing - all unqualified and qualified names are translated using the current import rules. When no alias is available all unqualified and qualified names have the current namespace prepended. Constants and functions have fallbacks to global namespace for unqualified names.

Importing and Aliasing Impacts They don't cost you anything, they are a kind of memory mapping for the PHP interpreter The classes imported aren't effectively loaded into memory unless the class itself is used Added bonus when importing all the classes used at the top of the file is you get A quick dependency overview. There are static tools being developed which will read those dependencies

Explicitly Loading from current <?php namespace Nbe ; use Exception ; const ERROR_INFO = 10; try { try { if (1===1) { throw new Exception ('instantiates Exception'); } } catch (Exception $e) { throw new namespaceException ('instantiates NbeException', ERROR_INFO, $e); } } catch ( namespaceException $e) { echo 'error: '.$e->getMessage(); echo PHP_EOL; echo 'nested exception error: '.$e-> getPrevious() ->getMessage(); } with namespace keyword <?php namespace Nbe ; class Exception extends Exception {} ?>

Coming to an end, but first some Timeline changes PHP4 class constructor has the same name as the class > PHP5 class constructor is __construct but accepts PHP4 convention >5.3 namespaces are introduced, nothing changes >= 5.3.3 Backward compatibility change. Only __construct is now regarded as the constructor for namespaced code.

And a quick recap on WHY Readability Dependencies can be indicated easily System functions and constants can be overwritten It is the future, evolve with the language or loose it The market will soon require the namespace skill

And some cool resources The PHP manual http://www.php.net/namespaces Ralph Schindlers namespace convert tool https://github.com/ralphschindler/PHPTools Plus comments on it by Cal Evans http://blog.calevans.com/2010/03/27/zends-new-namespace-converter/ Google: php namespaces http://www.google.be/search?q=php+namespaces Zend Framework 2.0 Cookbook http://blog.nickbelhomme.com/php/zend-framework-2-0-cookbook_324

And we reached the end, Any questions?

The End! THANK YOU [email_address] Slideshare, Twitter, IRC: NickBelhomme http://blog.nickbelhomme.com

Photo Credits Photos rights reserved by Sweetie187 , webtreats, royblumenthal, Brad montgomery, ktylerconk, vegetarians-dominate-meat-eaters-01, endless lazlo, DebilzBG, J. Star, quadrant6ix, notemily taken from Flickr.com

Mastering PHP Namespaces PFCongres11

by Nick Belhomme on Sep 17, 2011

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Mastering PHP Namespaces PFCongres11 — Presentation Transcript