PHP4 íå áûëî âîçìîæíîñòè ðàçûìåíîâàíèÿ (dereferencing) îáúåêòîâ, âîçâðàùàåìûõ ôóíöèåé.  PHP5 òàêàÿ âîçìîæíîñòü ââåäåíà, ÷òî ïîçâîëÿåò âûçûâàòü ìåòîäû âîçâðàùàåìûõ îáúåêòîâ, îïåðèðóÿ íåïîñðåäñòâåííî ñ ðåçóëüòàòîì âûïîëíåíèÿ ôóíêöèè:

class Circle {
 function draw() {
 print "Circlen";
 }
}
 
class Square {
 function draw() {
 print "Squaren";
 }
}

function ShapeFactoryMethod($shape) {
 switch ($shape) {
 case "Circle": 
 return new Circle();
 case "Square": 
 return new Square();
 }
}

ShapeFactoryMethod("Circle")->draw();
ShapeFactoryMethod("Square")->draw();
?>

Èíèöèàëèçàöèÿ ñòàòè÷åñêèõ ïåðåìåííûõ-ýëåìåíòîâ ñòàòè÷åñêèõ êëàññîâ

Ïðèìåð:

class foo {
 static $my_static = 5;
 public $my_prop = 'bla';
}

print foo::$my_static;
$obj = new foo;
print $obj->my_prop;
?>

Ñòàòè÷åñêèå ìåòîäû

 PHP5 êëþ÷åâîå ñëîâî "static" ìîæíî èñïîëüçîâàòü äëÿ îïðåäåëåíèÿ ñòàòè÷åñêîãî ìåòîäà, ÷òî ïîçâîëÿåò âûçûâàòü ìåòîä âíå êîíòåêñòà îáúåêòà.

Ïðèìåð:

class Foo {
 public static function aStaticMethod() {
 // ...
 }
}

Foo::aStaticMethod();
?>

Ïñåâäî-ïåðåìåííàÿ $this âíóòðè ìåòîäà, îáúÿâëåííîãî ñòàòè÷åñêèì, íåäîñòóïíà (òàê êàê ïðè âûçîâå ñòàòè÷åñêîãî ìåòîäà íåèçâåñòíî, â êîíòåêñòå êàêîãî ýêçåìïëÿðà êëàññà åå èñïîëüçîâàòü, äà è âïîëíå âîçìîæíî, ÷òî íà ìîìåíò âûçîâà èõ íå ñóùåñòâóåò âîîáùå - [fixxxer]).

Êëþ÷åâîå ñëîâî instanceof

 PHP5 ââåäåíî êëþ÷åâîå ñëîâî instanceof, ïîçâîëÿþùåå îïðåäåëèòü, ÿâëÿåòñÿ èëè íå ÿâëÿåòñÿ îáúåêò ýêçåìïëÿðîì êëàññà, ýêçåìïëÿðîì, ïðîèçâîäíûì îò êëàññà, èëè æå ðåàëèçàöèåé èíòåðôåéñà.

Ïðèìåð:

class baseClass { }

$a = new baseClass;

if ($a instanceof basicClass) {
 echo "Hello World";
}
?>

Ñòàòè÷åñêèå ïåðåìåííûå ôóíêöèé

Ñòàòè÷åñêèå ïåðåìåííûå òåïåðü îáðàáàòûâàþòñÿ íà ýòàïå êîìïèëÿöèè, ÷òî ïîçâîëÿåò ïðèñâàèâàòü èì çíà÷åíèÿ ïî ññûëêå. Ýòî èçìåíåíèå òàêæå çíà÷èòåëüíî ïîâûøàåò ïðîèçâîäèòåëüíîñòü, íî îçíà÷àåò, ÷òî êîñâåííûå ññûëêè íà ñòàòè÷åñêèå ïåðåìåííûå áîëüøå íå áóäóò ðàáîòàòü.

Äëÿ ïàðàìåòðîâ, ïåðåäàâàåìûõ ïî ññûëêå, òåïåðü ìîæíî óêàçàòü çíà÷åíèÿ ïî óìîë÷àíèþ.

Ïðèìåð:

function my_function(&$var = null) {
 if ($var === null) {
 die("$var needs to have a value");
 }
}
?>

__autoload()

Ôóíêöèÿ __autoload() âûçûâàåòñÿ àâòîìàòè÷åñêè â ñëó÷àå, êîãäà ïðîèñçîäèò ïîïûòêà ñîçäàíèÿ íåîïðåäåëåííîãî êëàññà. Èìÿ êëàññà ïåðåäàåòñÿ ôóíêöèè __autoload() â êà÷åñòâå åäèíñòâåííîãî àðãóìåíòà.

Ïðèìåð:

function __autoload($className) {
 include_once $className . ".php";
}

$object = new ClassName;
?>

Ïåðåãðóçêà âûçîâîâ ìåòîäà è äîñòóïà ê ñâîéñòâàì

Êàê âûçîâû ìåòîäîâ, òàê è îïåðàöèè äîñòóïà ê ñâîéñòâàì ìîãóò áûòü ïåðåãðóæåíû ñ èñïîëüçîâàíèåì ìåòîäîâ __call(), __get() è __set().

Ïðèìåð: __get() è __set()

class Setter {
 public $n;
 public $x = array("a" => 1, "b" => 2, "c" => 3);

 function __get($nm) {
 print "Getting [$nm]n";

 if (isset($this->x[$nm])) {
 $r = $this->x[$nm];
 print "Returning: $rn";
 return $r;
 } else {
 print "Nothing!n";
 }
 }

 function __set($nm, $val) {
 print "Setting [$nm] to $valn";

 if (isset($this->x[$nm])) {
 $this->x[$nm] = $val;
 print "OK!n";
 } else {
 print "Not OK!n";
 }
 }
}

$foo = new Setter();
$foo->n = 1;
$foo->a = 100;
$foo->a++;
$foo->z++;
var_dump($foo);
?>

Ïðèìåð: __call()

class Caller {
 var $x = array(1, 2, 3);

 function __call($m, $a) {
 print "Method $m called:n";
 var_dump($a);
 return $this->x;
 }
}

$foo = new Caller();
$a = $foo->test(1, "2", 3.4, true);
var_dump($a);
?>

Èòåðàòîðû

Äëÿ îáúåêòà ìîæíî óêàçàòü èòåðàòîð, êîòîðûé áóäåò èñïîëüçîâàí ïðè ïðèìåíåíèè êëàññà â îïåðàòîðå foreach. Ïî óìîë÷àíèþ èòåðàöèÿ ïðîèñõîäèò ïóòåì ïåðåáîðà âñåõ ñâîéñòâ.

Ïðèìåð:

class Foo {
 var $x = 1;
 var $y = 2;
}

$obj = new Foo;

foreach ($obj as $prp_name => $prop_value) {
 // using the property
}
?>

Êàæäûé êëàññ, ýêçåìïëÿðû êîòîðîãî ìîæíî èñïîëüçîâàòü ñ îïåðàòîðîì foreach, äîëæåí ðåàëèçîâûâàòü ïóñòîé èíòåðôåéñ Traversable. Äðóãèìè ñëîâàìè, ëþáîé îáúåêò, êîòîðîûé ðåàëèçóåò Traversable, ìîæíî èñïîëüçîâàòü ñ foreach.

Èíòåðôåéñû IteratorAggregate è Iterator ïîçâîëÿþò óêàçàòü ïîâåäåíèå êëàññà ïðè åãî èñïîëüçîâàíèè ñ îïåðàòîðîì foreach. Ïåðâûé èíòåðôåéñ ïðåäîñòàâëÿåò åäèíñòâåííûé ìåòîä getIterator(), êîòîðûé äîëæåí âîçâðàùàòü ìàññèâ èëè îáúåêò, êîòîðûé ëèáî ðåàëèçóåò èíòåðôåéñ Iterator, ëèáî ÿâëÿåòñÿ îáúåêòîì âñòðîåííîãî êëàññà, èìåþùåãî èòåðàòîð.

Ïðèìåð:

class ObjectIterator implements Iterator {

 private $obj;
 private $num;

 function __construct($obj) {
 $this->obj = $obj;
 }
 function rewind() {
 $this->num = 0;
 }
 function hasMore() {
 return $this->num < $this->obj->max;
 }
 function key() {
 return $this->num;
 }
 function current() {
 switch($this->num) {
 case 0: return "1st";
 case 1: return "2nd";
 case 2: return "3rd";
 default: return $this->num."th";
 }
 }
 function next() {
 $this->num++;
 }
}

class Object implements IteratorAggregate {

 public $max = 3;

 function getIterator() {
 return new ObjectIterator($this);
 }
} 

$obj = new Object;

// this foreach ...
foreach($obj as $key => $val) {
 echo "$key = $valn";
}

// matches the following 7 lines with the for directive.
$it = $obj->getIterator();
for($it->rewind(); $it->hasMore(); $it->next) {
 $key = $it->current();
 $val = $it->key();
 echo "$key = $valn";
}
unset($it);
?>

Äàííûé ïðèìåð âåñüìà èíòåðåñòåí, òàê êàê äåìîíñòðèðóåò èñïîëüçîâàíèå âñåõ àáñòðàêòíûõ ìåòîäîâ, îáúÿâëåííûõ â èíòåðôåéñàõ Iterator è IteratorAggregate ñîîòâåòñòâåííî.

Íîâàÿ êîíñòàíòà __METHOD__

Íîâàÿ ïñåâäî-êîíñòàíòà __METHOD__ ñîäåðæèò òåêóùèå èìåíà êëàññà è ìåòîäà, åñëè èñïîëüçóåòñÿ âíóòðè ìåòîäà, è èìÿ ôóíêöèè, åñëè èñïîëüçóåòñÿ âíå êëàññà.

Ïðèìåð:

Example

class Foo {
 function Show() {
 echo __FILE__ . '(' . __LINE__ . ')' . __METHOD__;
 }
}
function Test() {
 echo __FILE__ . '(' . __LINE__ . ')' . __METHOD__;
}
?>

Íîâûé ìåòîä __toString()

Íîâûé ìåòîä __toString() ïîçâîëÿåò ïåðåãðóçèòü ïðåîáðàçîâàíèå òèïà "îáúåêò->ñòðîêà".

Ïðèìåð:

class Foo {
 function __toString() {
 return "What ever";
 }
}

$obj = Foo;

$str = (string) $obj; // âûçûâàåòñÿ __toString()

echo $obj; // âûçûâàåòñÿ __toString()
?>

Ê ñîæàëåíèþ, íà äàííûé ìîìåíò ìåòîä _toString ðàáîòàåò òîëüêî ïðè èñïîëüçîâàíèè â êîíòåêñòå îïåðàòîðà echo/print.

Reflection API

PHP5 âêëþ÷àåò â ñåáÿ reflection API, ïðåäîñòàâëÿþùèé âîçìîæíîñòü ðåâåðñ-èíæèíèðèíãà êëàññîâ, èíòåðôåéñîâ, ôóíêöèé, ìåòîäîâ, à òàêæå ðàñøèðåíèé (extensions).

Reflection API òàêæå ïðåäîñòàâëÿåò äîñòóï ê doc-êîììåíòàðèÿì ôóíêöèé, êëàññîâ è ìåòîäîâ.

Ïðàêòè÷åñêè âñå àñïåêòû ÎÎ-êîäà ìîãóò áûòü îòðàæåíû ñ ïîìîùüþ reflection API. Reflaction API äîêóìåíòèðóåòñÿ îòäåëüíî.

Ïðèìåð:

class 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');
?>

Íîâûé äèñïåò÷åð ïàìÿòè

 PHP5 èñïîëüçóåòñÿ íîâûé äèñïåò÷åð ïàìÿòè, áîëåå ýôôåêòèâíî ðàáîòàþùèé â ìóëüòèòðýäîâîé ñðåäå, òàê êàê îí íå èñïîëüçóåò ìóòåêñû (mutexes) äëÿ îñóùåñòâëåíèÿ áëîêèðîâàíèÿ/ðàçáëîêèðîâàíèÿ (lock/unlock) ïðè îïåðàöèÿõ âûäåëåíèÿ/îñâîáîæäåíèÿ ïàìÿòè (allocation/deallocation).