PHP 5 and the new OO features for enterprise

solutions, part 1Marcus Börger

international PHP2003 conference

Marcus Börger PHP5 2

Overview

PHP5 vs PHP4

Is PHP5 revolutionary?

PHP 5 OOWhy is OO a good thing?

Marcus Börger PHP5 3

Revamped OO Model

PHP5 has really good OOBetter code reuseBetter for team developmentEasier to refactorSome patterns lead to much more efficient codeFits better in marketing scenarios

Marcus Börger PHP5 4

PHP 4 and OO ?

Poor Object modelMethods

No visibilityNo abstracts, No finalStatic without declaration

PropertiesNo default valuesNo static properties

InheritanceNo abstract, final inheritance, no interfaces

Object handlingCopied by valueNo destructors

Marcus Börger PHP5 5

ZE2's revamped object modelObjects are referenced by identifiersConstructors and DestructorsStatic membersDefault property valuesConstantsVisibilityInterfacesFinal and abstract membersInterceptorsExceptionsReflection APIIterators

Marcus Börger PHP5 6

Objects are no longer copied by defaultObjects may be copied using __clone()

<?php

class Object {};

$obj = new Object();

$ref = $obj;

$dup = $obj->__clone();

?>

Objects referenced by identifiers

Class Object

$obj $ref $dup

Instance 1 Instance 2

Marcus Börger PHP5 7

Constructors/Destructors control object lifetimeConstructors may have both new OR old style namesDestructors are called when deleting last reference

<?php

class Object {function __construct() {}function __destruct() {}

}$obj = new Object();unset($obj);

?>

Constructors and Destructors

Marcus Börger PHP5 8

Parents must be called manually

<?phpclass Base {

function __construct() {}function __destruct() {}

}class Object extends Base {

function __construct() {parent::__construct();

}function __destruct() {

parent::__destruct();}

}$obj = new Object();unset($obj);?>

Constructors and Destructors

Marcus Börger PHP5 9

Properties can have default valuesBound to the class not to the objectDefault values cannot be changed but overwritten

<?php

class Object {var $prop = "Hello\n";

}

$obj1 = new Object;$obj1->prop = "Hello World\n";

$obj2 = new Object;echo $obj2->prop; // Hello

?>

Default property values

Class Object$prop/default

$obj2

Instance 2$prop

$obj1

Instance 1$prop

Marcus Börger PHP5 10

Static methods and propertiesBound to the class not to the objectCan be initialized

<?phpclass Object {var $pop;static $stat = "Hello\n";static function test() {echo self::$stat;

} }Object::test();$obj1 = new Object;$obj2 = new Object;?>

Static members

Class Object$stat

$obj2

Instance 2$prop

$obj1

Instance 1$prop

Marcus Börger PHP5 11

New pseudo constants__CLASS__ shows the current class name__METHOD__ shows class and method or functionSelf references the class itselfParent references the parent class$this references the object itself<?phpclass Base {

static function Show() {echo __FILE__.'('.__LINE__.'):'.__METHOD__."\n";

}}class Object extends Base {

static function Use() {Self::Show();Parent::Show();

} static function Show() {

echo __FILE__.'('.__LINE__.'):'.__METHOD__."\n";}

}?>

Marcus Börger PHP5 12

Controlling member visibility / Information hidingA derived class does not know inherited privatesAn inherited protected member can be made public

<?phpclass Base {public $a;protected $b;private $c;

}class Derived extends Base {public $a;public $b;private $c;

}?>

Visibility

Base$a$b$c

Derived

$a$b$cBase::$c

Marcus Börger PHP5 13

Constructor visibility

A protected constructor prevents instantiation

<?phpclass Base {

protected function __construct() {}

}class Derived extends Base {

// constructor is still protectedstatic function getBase() {

return new Base; // Factory pattern}

}class Three extends Derived {

public function __construct() {}

}?>

Marcus Börger PHP5 14

Clone visibility

A protected __clone prevents external cloning

<?phpclass Base {

protected function __clone($that) {}

}class Derived extends Base {

public function __clone($that) {return new Base;

}public static function copyBase($that) {

return Base::__clone($that);}

}?>

A protected __clone prevents external cloningA private final __clone prevents cloning

<?phpclass Base {

private final function __clone($that) {}

}class Derived extends Base {

// public function __clone($that) {// return new Base; // }// public static function copyBase($that) {// return Base::__clone($that);// }

}?>

Marcus Börger PHP5 15

ConstantsConstants are read only static propertiesConstants are always public

<?phpclass Base {const greeting = "Hello\n";

}class Dervied extends Base {const greeting = "Hello World\n";static function func() {

echo parent::greeting; }

}echo Base::greeting;echo Derived::greeting;Derived::func();?>

Marcus Börger PHP5 16

Abstract members

Properties cannot be made abstractMethods can be abstract

They don’t have a bodyA class with an abstract method must be abstract

Classes can be made abstractThe class cannot be instantiated

<?phpabstract class Base {abstract function no_body();

}

class Derived extends Base {function no_body() { echo "Body\n"; }

}

?>

Marcus Börger PHP5 17

Final members

Methods can be made finalThey cannot be overwrittenThey are class invariants

Classes can be made finalThey cannot be inherited

<?phpclass Base {final function invariant() { echo "Hello\n"; }

}class Derived extends Base {}final class Leaf extends Derived {}?>

Marcus Börger PHP5 18

Interfaces describe an abstract class protocolClasses may inherit multiple Interfaces

<?phpinterface Drawable {function draw();

}class Line implements Drawable {function draw() {};}class Rect implements Drawable {function draw() {};}class Circle implements Drawable {function draw() {};}class Ellipse extends Circle {function draw() {};}?>

Interfaces

Drawable

RectLine Circle

Rect

Marcus Börger PHP5 19

Property types

Declared propertiesMay have a default valueCan have selected visibility

Implicit public propertiesDeclared by simply using them in ANY method

Virtual propertiesHandled by interceptor methods

Static properties

Marcus Börger PHP5 20

Object to String conversion

__toString(): automatic object string conversion

<?phpclass Object {

function __toString() {return 'Object as string';

}}

$o = new Object;

echo $o;

$str = (string) $o;?>

Marcus Börger PHP5 21

Interceptors

Allow to dynamically handle non class membersLazy initialization of propertiesSimulating Object aggregation, Multiple inheritance

<?phpclass Object {

protected $virtual;function __get($name) {

return @$virtual[$name];}function __set($name, $value) {

$virtual[$name] = $value;}function __call($func, $params) {

echo 'Could not call ' . __CLASS__ . '::' . $func . "\n";}

}?>

Marcus Börger PHP5 22

Exceptions

Respect these rules1. Exceptions are exceptions2. Never use exceptions for control flow3. Never ever use exceptions for parameter passing

<?phptry {

// your codethrow new Exception();

}catch (Exception $e) {

// exception handling}?>

Marcus Börger PHP5 23

Exception specialization

Exceptions should be specialized

<?phpclass YourException extends Exception {}try {

// your codethrow new YourException();

}catch (YourException $e) {

// exception handling}catch (Exception $e) {

// exception handling}?>

Marcus Börger PHP5 24

Exception specialization

Exception blocks can be nestedExceptions can be rethrown<?phpclass YourException extends Exception { }try {

try {// your codethrow new YourException();

}catch (YourException $e) {

// exception handlingthrow $e;

}catch (Exception $e) {

// exception handling}

}catch (YourException $e) {

// exception handling}?>

Marcus Börger PHP5 25

Constructor failure

Constructors do not return the created objectExceptions allow to handle failed constructors

<?phpclass Object {

function __construct() {throw new Exception;

}}try {

$o = new Object;}catch (exception $e) {

echo "Object could not be instantiated\n";}?>

Marcus Börger PHP5 26

Reflection API

Can reflect nearly all aspects of your PHP codeFunctionsClasses, Methods, PropertiesExtensions

<?phpclass Foo {

public $prop;function Func($name) {

echo "Hello $name";}

}

reflection_class::export('Foo');reflection_object::export(new Foo);reflection_method::export('Foo', 'func');reflection_property::export('Foo', 'prop');reflection_extension::export('standard');?>

Marcus Börger PHP5 27

Iterators

Some objects can be iteratedOthers show their properties

<?php

class Object {public $prop1 = "Hello";public $prop2 = "World\n";

}

foreach(new Object as $prop) {echo $prop;

}

?>

Marcus Börger PHP5 28

<?phpclass Filter implements Iterator {

function __construct(Iterator $input)...function rewind()...function accept($value)...function hasMore()...function current()...function key()...function next()...

}?>

IteratorsInternal IteratorsUser Iterators

<?php$it = get_resource();foreach($it as $key=>$val) {// access data

}?>

<?phpinterface Iterator {

function rewind();function hasMore();function current();function key();function next();

}?>

<?php$it = get_resource();foreach(new Filter($it, $filter_param) as $key=>$val) {// access filtered data only

}?>

<?php$it = get_resource();for ($it->rewind(); $it->hasMore(); $it->next()) {

$value = $it->current(); $key = $it->key();}?>

Marcus Börger PHP5 29

PHP & UMLTraversable

Aggregate

+ getIterator () : Iterator

Iterator

+++++

rewind ()hasMore ()current ()key ()next ()

: void: boolean: mixed: mixed: void

Filter

+++++++

<<Implement>><<Implement>><<Implement>><<Implement>><<Implement>>

rewind ()hasMore ()current ()key ()next ()__construct (Iterator data)accept (mixed Value)

: void: boolean: mixed: mixed: void: void: boolean

IteratorImpl

+++++

<<Implement>><<Implement>><<Implement>><<Implement>><<Implement>>

rewind ()hasMore ()current ()key ()next ()

: void: boolean: mixed: mixed: void

Marcus Börger PHP5 30

PHP & UML

Marcus Börger PHP5 31

PHP & UML

Marcus Börger PHP5 32

Typehinting

PHP 5 allows to easily force a type of a parameterBeta 1 and beta 2 allow NULL with typehintsBeta 3 will have a syntax to decide about NULL

<?phpclass Object {

public function compare(Object $other) {// Some code here

}}?>

Marcus Börger PHP5 33

New extensions

New extensionsFFIDOMMySQLiPDOPIMPSimpleXMLSPLSQLiteXML + XSL