This document discusses how to decouple objects using standard interfaces in PHP. It covers reasons for using interfaces like encapsulation and reuse. It provides examples of implementing interfaces, extending interfaces, and validating interface usage. It also discusses common interface methods, dynamic properties, magic methods, iterators, observers and more standard PHP interfaces.

1. IPC Spring 2013IPC Spring 2013
Decoupling Objects With
Standard Interfaces

2. About MeAbout Me
● Thomas Weinert
● papaya Software GmbH
● papaya CMS
● Twitter: @ThomasWeinert
● Web: http://www.a-basketful-of-papayas.net

3. InterfacesInterfaces
● By Declaration
● By Convention
● Magic Methods

4. ReasonsReasons
● Encapsulation
● Reuse
● S.O.L.I.D.

5. ImplementImplement
class Foo
implements
Countable,
IteratorAggregate {
}

6. ExtendExtend
interface Foo extends IteratorAggregate {
}

7. ValidateValidate
if ($foo instanceOf Traversable) {
}

8. Type HintsType Hints
function bar(Traversable $foo) {
}

9. InterfacesInterfaces
By Convention

10. Object InitializationObject Initialization
● Magic Methods
● __construct()
● __destruct()
● __clone()
● __sleep()/__wakeup() → Serializeable
● __set_state()

11. __toString__toString
● Cast an object to string
/**
* Casting the object to string will
*return the last value
* @return string
*/
public function __toString() {
return (string)end($this->_values);
}

12. Dynamic PropertiesDynamic Properties
● $object->value = 123
● $value = $object->value;
● $object->setValue(123);
● $value = $object->getValue();

13. Dynamic PropertiesDynamic Properties
● __isset()
● __get()
● __set()
● __unset()

14. __isset()__isset()
/**
* @param string $name
* @return boolean
*/
public function __isset($name) {
switch ($name) {
case 'name' :
case 'value' :
case 'values' :
return TRUE;
}
return FALSE;
}

15. __get()__get()
/**
* @param string $name
* @throws InvalidArgumentException
* @return mixed
*/
public function __get($name) {
switch ($name) {
case 'name' :
return $this->_name;
case 'value' :
return end($this->_values);
case 'values' :
return $this->_values;
}
throw new LogicException(
sprintf(
'Can not read non existing property: %s::$%s',
__CLASS__,
$name
)
);
}

16. __set()__set()
/**
* @param string $name
* @param string|array|Traversable $value
* @throws LogicException
*/
public function __set($name, $value) {
switch ($name) {
case 'name' :
$this->setName($value);
return;
case 'value' :
$this->setData((string)$value);
return;
case 'values' :
$this->setData($value);
return;
}
throw new LogicException(
sprintf('Can not write non existing property: %s::$%s',
__CLASS__, $name
...

17. __call/__callStatic__call/__callStatic
Dynamic Methods/Functions

18. Generic CallbacksGeneric Callbacks
class MyEvents extends Events {
public function __construct() {
parent::__construct(['example' => 21]);
}
}
$my = new MyEvents();
echo $my->onExample(), "n"; //21
$my->onExample = function () {
return 42;
};
echo $my->onExample(), "n"; //42
$my->onExample = 23;
echo $my->onExample(), "n"; //23

19. PHP DocumentorPHP Documentor
/*
* …
*
* @property Callable $onExample
* @method mixed onExample()
*/
class MyEvents extends Events {
public function __construct() {
parent::__construct(['example' => 21]);
}
}

20. CallableCallable
● 'function'
● array($object, 'method')
● function() {}
● class {}

21. __invoke__invoke
● Functors
● Callable

22. Callback ListsCallback Lists
...
$queries = IoDeferred::When(
$mysqlOne("SELECT 'Query 1', SLEEP(5)")
->done(
function($result) use ($time) {
var_dump(iterator_to_array($result));
var_dump(microtime(TRUE) - $time);
}
),
$mysqlTwo("SELECT 'Query 2', SLEEP(1)")
->done(
function($result) use ($time) {
var_dump(iterator_to_array($result));
var_dump(microtime(TRUE) - $time);
}
)
);

23. Functor ExampleFunctor Example
class DatabaseResultDebugger {
private $_startTime = 0;
public function __construct($startTime) {
$this->_startTime = $startTime;
}
public function __invoke($result) {
var_dump(iterator_to_array($result));
var_dump(microtime(TRUE) - $this->_startTime);
}
}

24. Callback HandlersCallback Handlers
$queries = IoDeferred::When(
$mysqlOne("SELECT 'Query 1', SLEEP(5)")
->done(
new DatabaseResultDebugger($time)
),
$mysqlTwo("SELECT 'Query 2', SLEEP(1)")
->done(
new DatabaseResultDebugger($time)
)
);

25. More Callback HandlersMore Callback Handlers
$queries = IoDeferred::When(
$mysqlOne("SELECT 'Query 1', SLEEP(5)")
->done(
new ConcreteDatabaseResultHandler()
)
->done(
new DatabaseResultDebugger($time)
),
$mysqlTwo("SELECT 'Query 2', SLEEP(1)")
->done(
new DatabaseResultDebugger($time)
)
);

26. Predeclared Interfaces

27. SerializeableSerializeable
● Usage
● serialize($object)
● unserialize($string);
● Methods
● $object->serialize()
● $object->unserialize($string);

28. JsonSerializableJsonSerializable
● Usage
● json_encode()
● Method
● $object->jsonSerialize()

29. ArrayAccessArrayAccess
● [] -Syntax
● Validation
● Conversion
● Lazy Initialization

30. ArrayAccess MethodsArrayAccess Methods
● offsetExists()
● offsetGet()
● offsetSet()
● offsetUnset()

31. OffsetExists()OffsetExists()
/**
* @param integer $offset
* @return boolean
*/
public function offsetExists($offset) {
return array_key_exists($offset, $this->_values);
}

32. OffsetGet()OffsetGet()
/**
* @param integer $offset
*/
public function offsetGet($offset) {
return $this->_values[$offset];
}

33. OffsetSet()OffsetSet()
/**
* @param integer $offset
* @param string $value
*/
public function offsetSet($offset, $value) {
if (NULL === $offset) {
$this->_values[] = $value;
} else {
$this->_values[$offset] = $value;
}
}

34. OffsetUnset()OffsetUnset()
/**
* @param integer $offset
*/
public function offsetUnset($offset) {
unset($this->_values[$offset]);
}

35. Array DereferencingArray Dereferencing
echo $object->foo()[0];

36. CountableCountable
● count($foo)
class DatabaseResult implements Countable {
...
public function count() {
return $this->_count;
}
...
}

37. TraversableTraversable
● foreach
● Iterator
● IteratorAggregate

38. Iterator InterfacesIterator Interfaces
Traversable
Iterator
OuterIterator
IteratorAggregate
RecursiveIteratorSeekableIterator
SPL

39. Iterator functionsIterator functions
● foreach()
● iterator_to_array()
● iterator_count()
● iterator_apply()

40. IteratorIterator
● rewind()
● next()
● valid()
● current()
● key()

41. IteratorAggregateIteratorAggregate
● getIterator()
class Foo implements IteratorAggregate {
private $_items = array();
public function __construct(array $items) {
$this->_items = $items;
}
public function getIterator() {
return new ArrayIterator($this->_items);
}
}

42. Predefined IteratorsPredefined Iterators
● ArrayIterator
● EmptyIterator
● RegexIterator
● …

43. Nest IteratorsNest Iterators
● IteratorIterator
● AppendIterator
● CallbackFilterIterator
● ...

44. RecursiveIteratorRecursiveIterator
● List with Children
$items = [
1 => '1',
2 => '1.1',
3 => '2'
];
$structure = [
0 => [1, 3],
1 => [2]
];

45. Inherit from IteratorIteratorInherit from IteratorIterator
class Bar
extends IteratorIterator
implements RecursiveIterator {
private $_items = [];
private $_structure = [];
public function __construct($items, $structure, $parent = 0) {
$siblings = [];
if (!empty($structure[$parent])) {
foreach ($structure[$parent] as $id) {
if (isset($items[$id])) {
$siblings[$id] = $items[$id];
}
}
}
parent::__construct(new ArrayIterator($siblings));
$this->_items = $items;
$this->_structure = $structure;
}
...

46. hasChildren()hasChildren()
public function hasChildren() {
return
$this->valid() &&
isset($this->_structure[$this->key()]);
}

47. getChildren()getChildren()
public function getChildren() {
if ($this->hasChildren()) {
return new $this(
$this->_items,
$this->_structure,
$this->key()
);
} else {
return new $this([], []);
}
}

48. RecursiveIteratorIteratorRecursiveIteratorIterator
● Iterator for RecursiveIterator
$iterator = new RecursiveIteratorIterator(
new Bar($items, $structure),
RecursiveIteratorIterator::SELF_FIRST
);
foreach ($iterator as $element) {
echo str_repeat('*', $iterator->getDepth() + 1);
echo $element;
echo "n";
}

49. ResultResult
* 1
** 1.1
* 2
● No recursive function call
● Works with Traversable/ArrayAccess
● Allows for Lazy Initalization

50. ObserverObserver
Subject
Observer 2 Observer 2Observer 2

51. ObserverObserver
CMS Page published
Log Action Announce To
Webservice
Invalidate
Cache

52. ObserverObserver
● SplObserver
● update()
● SplSubject
● attach()
● detach()
● notify()

53. Thank YouThank You
● Twitter: @ThomasWeinert
● https://joind.in/8807