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All rights reserved. Zend Technolo

Using PHP 5.3 Namespacesfor Fame and Fortune

Matthew Weier O'PhinneyProject Lead, Zend Framework

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All rights reserved. Zend Technologies, Inc.

What are namespaces?

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What are namespaces?

"A way in which to grouprelated classes, functions and constants

http://php.net/namespace

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Basics

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Namespace Separator

\

Get over it!

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What can live in namespaces

Classes

Constants Functions

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Declaring namespaces

Single line declaration

namespace Zend;namespace Zend;

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Block declaration

namespace Zend{}namespace Phly{}

namespace Zend{}namespacePhly{}

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Subnamespaces

Separate the subnamespaces using thenamespace separator

namespace Zend\Log;

namespace Zend\Log\Writer;

namespace Zend\Log;


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Referring to namespaced elements

From non-namespaced code:

$class = new My\Registry();$class = new My\Log\Logger();My\str_split($s); // function call$val = My\APIKEY; // constant value

$class = new My\Registry();$class=new My\Log\Logger();My\str_split($s);// function call$val= My\APIKEY;// constant value

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From code using the same namespace:

namespace My;

$class = new Registry();$class = new Log\Logger();str_split($s); // function call$val = APIKEY; // constant value

namespace My;

$class=new Registry();$class=new Log\Logger();str_split($s);// function call$val= APIKEY;// constant value

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From code in a different namespace:

namespace Your;

$class = new \My\Registry();$class = new \My\Log\Logger();\My\str_split($s); // function call$val = \My\APIKEY; // constant value

namespace Your;

$class=new\My\Registry();$class=new\My\Log\Logger();\My\str_split($s);// function call$val=\My\APIKEY;// constant value

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Using namespaced code:

Prefixing with a namespace separator resolvesas a fully qualified name

Resolution order:

Globally qualified: known; otherwise:

Current namespace, or relative to it(Classes, functions, constants)

Global namespace(functions, constants)

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This means:

You can override system functions withinnamespaces!

namespace My;

function str_split($string, $splitlen = 2){ return preg_split('/\W/', $string, $splitlen);}

$a = str_split("Foo, Bar"); // invokes My\str_split/* array (* 0 => 'Foo',* 1 => ' Bar',* )*/

namespace My;

functionstr_split($string,$splitlen=2){ returnpreg_split('/\W/',$string,$splitlen);}

$a=str_split("Foo, Bar");// invokes My\str_split(/* array (* 0 => 'Foo',* 1 => ' Bar',* )*/

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Importing namespaces

A way to bring code from another namespaceinto the current namespace.

Import:

Classes

Other namespaces

Keyword used is use

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namespace My;

class Registry {}

namespace Your;use My; // imports namespaceuse My\Registry; // imports class

namespace My;

classRegistry{}

namespace Your;use My; // imports namespaceuse My\Registry;// imports class

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Using imported code

namespace Your;

use My; // imports namespace$r = new My\Registry();

namespace Your;use My\Registry; // imports class$r = new Registry();

namespace Your;use

My; // imports namespace$r=new My\Registry();

namespace Your;use My\Registry;// imports class$r=new Registry();

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Aliasing

"import namespace or class, but refer to itusing this name"

PHP utilizes the as keyword to alias

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Aliasing

namespace Your;

use My as m;$r = new m\Registry();

namespace Your;use My\Registry as reg;$r = new reg();

namespace Your;use

Myas

m;$r=new m\Registry();

namespace Your;use My\Registryas reg;$r=new reg();

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Make typehinting more semantic!

namespace App;

use Zend\EventManager\EventManager as Events;

class Foo{ public function events(Events $events = null)

{ if ($eventsinstanceof Events) { $this->events = $events;

} elseif (!$this->events instanceof Events) $this->events = new Events(__CLASS__);}

return$this->events;}

}

namespace App;useZend\EventManager\EventManagerasEvents;

classFoo{ public functionevents(Events$events=null) { if($eventsinstanceofEvents) { $this->events=$events; }elseif(!$this->eventsinstanceofEvents) { $this->events=newEvents(__CLASS__); } return$this->events; }}

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Importing multiple namespaces/classes

Multiple use statements

namespace Their;use My;use Your;


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Or use a comma (,) to separate statements

namespace Their;use My,

Your;


Your;

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With aliases

namespace Their;

use My as m, // aliasedYour; // not aliased

namespace Their;

useMyas m,// aliasedYour; // not aliased

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What namespace are you in?

__NAMESPACE__

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Comprehensive example

namespace My\Package;const APIKEY = 1;function get($data) {}class Service {}

namespace My\OtherPackage;const APIKEY = 2;

function get($data) {}class Service {}

namespace My\Package;constAPIKEY=1;function get($data) {}classService{}

namespace My\OtherPackage;constAPIKEY=2;

function get($data) {}classService{}

The setup:

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namespace Test;use My\Package\Service as PackageService,

My\OtherPackage;const APIKEY = 3;echo APIKEY; // 3echo OtherPackage\APIKEY; // 2echo \My\Package\APIKEY; // 1

$s = new PackageService(); // My\Package\Service

$s = new Service(); // E_FATAL (no match)$s = new OtherPackage\Service();// My\OtherPackage\Service

get($baz); // E_FATAL (no matching function in// current namespace)

OtherPackage\get($baz); // My\OtherPackage\get()

namespace Test;use My\Package\Serviceas PackageService,

My\OtherPackage;constAPIKEY=3;echo APIKEY; // 3echo OtherPackage\APIKEY;// 2echo\My\Package\APIKEY; // 1

$s=new PackageService();// My\Package\Service$s=new Service(); // E_FATAL (no match)$s=new OtherPackage\Service();

// My\OtherPackage\Service

get($baz); // E_FATAL (no matching function in // current namespace)OtherPackage\get($baz);// My\OtherPackage\get()

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Pitfalls

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Referencing namespaced code in strings

Classes, constants, and functions referenced ina string MUSTbe fully qualified

No namespace separatorprefixis necessary

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Example 1

namespace My;// Assume My\Log\Logger is a defined class

$class = 'Log\Logger';$o = new$class; // E_FATAL; can't find

// relative names

$class = 'My\Log\Logger';$o = new$class; // Success

$class = '\My\Log\Logger';$o = new$class; // Also success,

// but not necessary


$class='Log\Logger';$o =new$class;// E_FATAL; can't find

// relative names

$class='My\Log\Logger';$o =new$class;// Success

$class='\My\Log\Logger';$o =new$class;// Also success,


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Example 2


$class = 'Log\Logger';if ($oinstanceof$class) { } // Fails; can't

// resolve class

$class = 'My\Log\Logger';if ($oinstanceof$class) { } // Success


$class='Log\Logger';if($oinstanceof$class) { }// Fails; can't

// resolve class

$class='My\Log\Logger';if($oinstanceof$class) { }// Success

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Why use namespaces?

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Code Organization: Filesystem

Namespace separator has an affinity for thedirectory separator

Suggests a 1:1 relationship with file system

namespace My\Log;class Logger {}/* My/Log/Logger.php (*nix)

My\Log\Logger.php (Windows) */

namespace My\Log;classLogger{}/* My/Log/Logger.php (*nix)


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Code Organization: By Responsibility

Interfaces

Use cases: i nsta nceof : $ c l a s s i n s t a n c e o f Ad a p t e r

i m pl e m ents : S o m e C l a s s i m p l e m e n t s Ad a p t e r

Natural language is easiest to understand

Natural language suggests a hierarchy

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interfaceT r a n s l a t o r \ Ad a p t e r

inT r a n s l a t o r / A d a p t e r . p h p

class T r a n s l a t o r \ Ad a p t e r \ Co n c r e t e A d a p t e r inT r a n s l a t o r / A d a p t e r / C o n c r e t e A d a p t e r . p h p

namespace Translator\Adapter;

use Translator\Adapter;

class ConcreteAdapter implements Adapter{}

namespace Translator\Adapter;

use Translator\Adapter;

classConcreteAdapterimplementsAdapter{}

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Takeaway: we're referencing the capabilities,not the language type

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Readability

When within a namespace, reference classesdirectly, keeping usage succinct

namespace Zend\Http;$client = new Client();

namespace Zend\Http;$client=newClient();

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Readability

Importing and aliasing make names moresuccinct

namespace Application;use Zend\Http\Client as HttpClient,

Zend\Logger\Logger;

$client = new HttpClient();$log = new Logger();

namespace Application;useZend\Http\ClientasHttpClient,

Zend\Logger\Logger;

$client=newHttpClient();$log =newLogger();

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Readability

Aliasing allows giving names context

namespace Application\Controller;

use Zend\Controller\Actionas ActionController;

class FooControllerextends ActionController {}


useZend\Controller\ActionasActionController;

classFooControllerextendsActionController{}

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Dependency declarations

Suggestion: import everyclass outside thecurrent namespace that you consume


use Zend\Controller\Actionas ActionController,

My\ORM\Mapper as DataMapper,My\Entity\BlogEntry,Zend\EventManager\EventManager;


useZend\Controller\ActionasActionController,

My\ORM\MapperasDataMapper,My\Entity\BlogEntry,

Zend\EventManager\EventManager;

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Imports are hints to the interpreter, and don'tcost anything

Helps to document dependencies up front

Allows static analysis to determinedependencies

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Resources

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PHP Manual: http://php.net/namespace

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Basically, a language-supported mechanism forgrouping these language features, as well as alanguage-supported mechanism for avoiding naming

conflicts.

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Namespace Separator

\

Get over it!

There are a ton of reasons why the backslash wasused, ranging from length of token to position of thetoken on most keyboards to previous use of other

tokens to understanding the scope of a givenoperator/operation visually. Just use it, and movealong.

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What can live in namespaces

Classes

Constants Functions

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Single line declaration

namespace Zend;namespace Zend;

You _can_ declare multiple namespaces in the samefile in this way, but it's not recommended

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Block declaration

namespace Zend{}namespace Phly{}

namespace Zend{}namespacePhly{}

This is the recommended way to declare multiplenamespaces when in a single file.

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Subnamespaces

Separate the subnamespaces using the

namespace separator

namespace Zend\Log;


namespace Zend\Log;


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From non-namespaced code:

$class = new My\Registry();$class = new My\Log\Logger();My\str_split($s); // function call$val = My\APIKEY; // constant value

$class = new My\Registry();$class=new My\Log\Logger();My\str_split($s);// function call$val= My\APIKEY;// constant value

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From code using the same namespace:

namespace My;

$class = new Registry();$class = new Log\Logger();str_split($s); // function call$val = APIKEY; // constant value

namespace My;

$class=new Registry();$class=new Log\Logger();str_split($s);// function call$val= APIKEY;// constant value

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From code in a different namespace:

namespace Your;

$class = new \My\Registry();$class = new \My\Log\Logger();\My\str_split($s); // function call$val = \My\APIKEY; // constant value

namespace Your;

$class=new\My\Registry();$class=new\My\Log\Logger();\My\str_split($s);// function call$val=\My\APIKEY;// constant value

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A way to bring code from another namespace

into the current namespace. Import:

Classes

Other namespaces

Keyword used is use

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namespace My;class Registry {}

namespace Your;use My; // imports namespaceuse My\Registry; // imports class

namespace My;

classRegistry{}

namespace Your;use My; // imports namespaceuse My\Registry;// imports class

Note: importing top-level namespaces in code with nonamespace has no effect and results in a warning.

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Using imported code

namespace Your;use My; // imports namespace$r = new My\Registry();

namespace Your;use My\Registry; // imports class$r = new Registry();

namespace Your;

use My; // imports namespace$r=new My\Registry();

namespace Your;use My\Registry;// imports class$r=new Registry();

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Aliasing

"import namespace or class, but refer to it

using this name" PHP utilizes the as keyword to alias

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Aliasing

namespace Your;use My as m;$r = new m\Registry();

namespace Your;use My\Registry as reg;$r = new reg();

namespace Your;

useMyas m;$r=new m\Registry();

namespace Your;use My\Registryas reg;$r=new reg();

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Make typehinting more semantic!

namespace App;

use Zend\EventManager\EventManager as Events;

class Foo{ public function events(Events $events = null)

{ if ($eventsinstanceof Events) { $this->events = $events;

} elseif (!$this->events instanceof Events) { $this->events = new Events(__CLASS__);

} return$this->events;

}}

namespace App;

useZend\EventManager\EventManagerasEvents;

classFoo{ public functionevents(Events$events=null) { if($eventsinstanceofEvents) { $this->events=$events; }elseif(!$this->eventsinstanceofEvents) { $this->events=newEvents(__CLASS__); } return$this->events; }}

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Multiple use statements



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Or use a comma (,) to separate statements


Your;


Your;

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With aliases

namespace Their;

use My as m, // aliasedYour; // not aliased

namespace Their;

useMyas m,// aliasedYour; // not aliased

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What namespace are you in?

__NAMESPACE__

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namespace My\Package;const APIKEY = 1;function get($data) {}class Service {}

namespace My\OtherPackage;const APIKEY = 2;function get($data) {}class Service {}

namespace My\Package;constAPIKEY=1;function get($data) {}classService{}

namespace My\OtherPackage;constAPIKEY=2;function get($data) {}classService{}

The setup:

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namespace Test;use My\Package\Service as PackageService,

My\OtherPackage;const APIKEY = 3;echo APIKEY; // 3echo OtherPackage\APIKEY; // 2echo \My\Package\APIKEY; // 1

$s = new PackageService(); // My\Package\Service$s = new Service(); // E_FATAL (no match)$s = new OtherPackage\Service();


get($baz); // E_FATAL (no matching function in// current namespace)

OtherPackage\get($baz); // My\OtherPackage\get()

namespace Test;use My\Package\Serviceas PackageService,

My\OtherPackage;constAPIKEY=3;echo APIKEY; // 3echo OtherPackage\APIKEY;// 2echo\My\Package\APIKEY; // 1

$s=new PackageService();// My\Package\Service$s=new Service(); // E_FATAL (no match)$s=new OtherPackage\Service();


get($baz

); // E_FATAL (no matching function in // current namespace)OtherPackage\get($baz);// My\OtherPackage\get()

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Classes, constants, and functions referenced in

a string MUSTbe fully qualified No namespace separatorprefixis necessary

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Example 1


$class = 'Log\Logger';$o = new$class; // E_FATAL; can't find

// relative names

$class = 'My\Log\Logger';$o = new$class; // Success

$class = '\My\Log\Logger';$o = new$class; // Also success,



$class='Log\Logger';$o =new$class;// E_FATAL; can't find

// relative names

$class='My\Log\Logger';$o =new$class;// Success

$class='\My\Log\Logger';

$o =new$class;// Also success,// but not necessary

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Example 2


$class = 'Log\Logger';if ($oinstanceof$class) { } // Fails; can't

// resolve class

$class = 'My\Log\Logger';if ($oinstanceof$class) { } // Success


$class='Log\Logger';if($oinstanceof$class) { }// Fails; can't

// resolve class

$class='My\Log\Logger';if($oinstanceof$class) { }// Success

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Code Organization: Filesystem

Namespace separator has an affinity for the

directory separator Suggests a 1:1 relationship with file system

namespace My\Log;class Logger {}/* My/Log/Logger.php (*nix)


namespace My\Log;classLogger{}/* My/Log/Logger.php (*nix)


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Interfaces

Use cases: i nst an c eof: $ c l a s s i n s t a n c e o f A d a p t er

i m pl e m ent s: S o m e C l a s s i m p l e m e n t s A d a p t e r

Natural language is easiest to understand

Natural language suggests a hierarchy

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Takeaway: we're referencing the capabilities,

not the language type

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Readability

When within a namespace, reference classes

directly, keeping usage succinctnamespace Zend\Http;$client = new Client();

namespace Zend\Http;$client=newClient();

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Readability

Importing and aliasing make names more

succinctnamespace Application;use Zend\Http\Client as HttpClient,

Zend\Logger\Logger;

$client = new HttpClient();$log = new Logger();

namespace Application;useZend\Http\ClientasHttpClient,

Zend\Logger\Logger;

$client=newHttpClient();$log =newLogger();

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Readability

Aliasing allows giving names context


use Zend\Controller\Actionas ActionController;

class FooControllerextends ActionController {}


useZend\Controller\ActionasActionController;

classFooControllerextendsActionController{}

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Suggestion: import everyclass outside the

current namespace that you consume


use Zend\Controller\Actionas ActionController,

My\ORM\Mapper as DataMapper,My\Entity\BlogEntry,Zend\EventManager\EventManager;


useZend\Controller\ActionasActionController,

My\ORM\MapperasDataMapper,My\Entity\BlogEntry,Zend\EventManager\EventManager;

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Imports are hints to the interpreter, and don't

cost anything Helps to document dependencies up front

Allows static analysis to determinedependencies

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Click to add title

PHP Manual: http://php.net/namespace

2011-03-02-namespaces-v2

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