This document summarizes magic methods in PHP that allow for custom object behavior. It discusses methods for stringification (__toString()), object lifecycle (__construct(), __destruct()), property overloading (__get(), __set(), etc.), method overloading (__call(), __callStatic()), serialization (__sleep(), __wakeup()), cloning (__clone(), __set_state()), and object invocation (__invoke()). Examples are provided for each method. Performance benchmarks at the end show that magic methods have negligible overhead compared to normal method calls.

1. Magic Methods: Spilling the Secret
By Matthew Barlocker

2. The Barlocker
● Chief Architect at Lucid
Software Inc
● Started using PHP in 2005
● Graduated with BS in CS from
BYU in 2008
● Developed software for the
following industries:
– Network Security
– Social Gaming
– Financial
– Productivity

3. Magic Methods
● All object methods beginning with '__' are reserved.
● To gain the magic functionality, define the method on the
class.
<?php
class MyClass {
private $var1 = 5;
public function doSomething() {
echo "hello!n";
}
}
<?php
class MyClass {
private $var1 = 5;
public function doSomething() {
echo "hello!n";
}
public function __toString() {
return 'This is a MyClass';
}
}

4. Magic Methods
● Stringification
● Lifecycle
● Property Overloading
● Method Overloading
● Serialization
● Cloning
● Object Invocation

5. Stringification
● __toString

6. __toString
● public string __toString()
● Called when an object is cast as a string.
● Throwing an exception inside this method will cause a
fatal error.
● No default implementation.

7. __toString
<?php
class NoTostringExample {
public $a = 1;
}
$obj = new NoTostringExample();
echo "Stringified " . $obj . "n";
?>
$ php notostring.php
PHP Catchable fatal error: Object of class NoTostringExample could not be
converted to string in notostring.php on line 8

8. __toString
<?php
class TostringExample {
public $a = 2;
public function __toString() {
return 'TostringExample(' . $this->a . ')';
}
}
$obj = new TostringExample();
echo "Stringified " . $obj . "n";
?>
$ php tostring.php
Stringified TostringExample(2)

9. __toString
<?php
class BadTostringExample {
public $a = 3;
public function __toString() {
echo 'TostringExample(' . $this->a . ')' . "n";
}
}
$obj = new BadTostringExample();
echo "Stringified " . $obj . "n";
?>
$ php badtostring.php
TostringExample(3)
PHP Catchable fatal error: Method BadTostringExample::__toString() must return a
string value in badtostring.php on line 11

10. Lifecycle
● __construct
● __destruct

11. __construct
● public void __construct($params, …)
● Called when an object is first initialized.
● Must explicitly call parent::__construct() in children.
● Default implementation does nothing.

12. __destruct
● public void __destruct()
● Called when an object is garbage collected.
● Must explicitly call parent::__destruct() in children.
● Default implementation does nothing.

13. __destruct
● public void __destruct()
● Called when an object is garbage collected.
● Must explicitly call parent::__destruct() in children.
● Default implementation does nothing.

14. __construct / __destruct
$ php construct.php
Starting
Construct
Ending
Destruct
<?php
class Construct {
public function __construct() {
echo "Constructn";
}
public function __destruct() {
echo "Destructn";
}
}
echo "Startingn";
$obj = new Construct();
echo "Endingn";
?>

15. __construct / __destruct
<?php
class MyDB {
private $connection = null;
public function __construct($host, $user, $pass) {
$this->connection = dbconnect($host, $user, $pass);
}
public function __destruct() {
$this->connection->close();
}
}

16. Property Overloading
● __get
● __set
● __isset
● __unset

17. __get
● public mixed __get($name)
● Called when an inaccessible property is read.
● Not called in chains. ($x = $obj->noexist = 5;)
● Default implementation emits a warning and returns null
or emits a fatal error.
● Does not apply to static context.

18. __set
● public void __set($name, $value)
● Called to write a value to an inaccessible property.
● Default implementation adds a public variable to the
class.
● Does not apply to static context.

19. __isset
● public mixed __isset($name)
● Triggered by calling isset() or empty() on inaccessible
properties
● Default implementation checks for existence of property
and ignores visibility.
● Does not apply to static context.

20. __unset
● public mixed __unset($name)
● Triggered by calling unset() on inaccessible properties
● Default implementation removes accessible properties.
● Does not apply to static context.

21. Property Test
See code from
http://www.php.net/manual/en/language.oop5.overloading.php#object.get

22. Method Overloading
● __call
● __callStatic

23. __call
● public mixed __call($name, $params)
● Called when invoking inaccessible methods from an
object context.

24. __callStatic
● public static mixed __callStatic($name, $params)
● Called when invoking inaccessible methods from a static
context.

25. __call / __callStatic
<?php
class MethodTest
{
public function __call($name, $arguments)
{
echo "Calling object method '$name' " . implode(', ', $arguments). "n";
}
public static function __callStatic($name, $arguments)
{
echo "Calling static method '$name' " . implode(', ', $arguments). "n";
}
}
$obj = new MethodTest;
$obj->runTest(1, 2, 3, 'in object context');
MethodTest::runTest(4, 5, 6, 'in static context'); // As of PHP 5.3.0
?>
$ php methodtest.php
Calling object method 'runTest' 1, 2, 3, in object context
Calling static method 'runTest' 4, 5, 6, in static context

26. Serialization
● __sleep
● __wakeup

27. __sleep
● public array __sleep()
● Called when serialize() is called on the object.
● Returns an array of field names to include in the serialized
version of the object.

28. __wakeup
● public void __wakeup()
● Called when unserialize() is called on the serialized
object.

29. __sleep / __wakeup
See code from
http://www.php.net/manual/en/language.oop5.magic.php#object.sleep

30. Cloning
● __clone
● __set_state

31. __clone
● public void __clone()
● Called after the object is initialized.
● Default implementation does nothing.

32. __clone
See code from
http://www.php.net/manual/en/language.oop5.cloning.php#object.clone

33. __set_state
● public static void __set_state($properties)
● Called for classes exported by var_export().

34. __set_state
See code from
http://www.php.net/manual/en/language.oop5.magic.php#object.set-state

35. Object Invocation
● __invoke

36. __invoke
● public mixed __invoke($params, ...)
● Called when the object is treated like a function.
– $obj(1,2,3);

37. __invoke
<?php
class CallableClass
{
public function __invoke($x)
{
var_dump($x);
}
}
$obj = new CallableClass;
$obj(5);
var_dump(is_callable($obj));
?>
$ php invoke.php
int(5)
bool(true)

38. Performance
● Each benchmark was run 10 times.
● Each run is shown as a different set of columns in the
graphs.
● Each run is exactly 1 million calls to the item being tested.

39. Performance

40. Performance

41. Performance

42. Performance

43. Performance

44. Performance

45. Thank you for your time.
Any Questions?

46. Lucid Software Inc
● Building the next generation of collaborative web
applications
● VC funded, high growth, profitable
● Graduates from Harvard, MIT, Stanford
● Team has worked at Google, Amazon, Microsoft
https://www.lucidchart.com/jobs